← Back to search

Protein Structures and Oligomeric States

Enter a protein name, UniProt accession or PDB ID. Name searches ask you to confirm the protein identity before related structures are queried.

Current Protein Identity：Q99216 New Search
43PDB entries
43Biological assembly
43chain/assembly records
Main Difference Dimensions in This Set
Different construct Different assembly state Different ligand/ion Different experimental conditions Different structure-quality metrics

Difference tags compare only the current result set; every original PDB and assembly record remains separate.

Related-Structure Differences

Each row represents one biological assembly in one PDB entry; multiple monomers of the same protein are listed separately.

PDB Entry Assembly / Oligomeric State Construct Mutations and Modifications Ligands, Ions and Non-polymers Experimental Method Experimental Conditions Structure Quality
5WLC The complete structure of the small subunit processome Deposited 2017-07-26 Assembly 1 Insufficient information Heteromer；Protein × 67 PDB declaration: 70-meric（70） Consistent with all polymers
Chain SO 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.7
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.80 Å
5WYJ Cryo-EM structure of the 90S small subunit pre-ribosome (Dhr1-depleted, Enp1-TAP, state 1) Deposited 2017-01-13 Assembly 1 Protein–RNA Heteromer；Protein × 61 PDB declaration: 64-meric（64） Consistent with all polymers
Chain P1 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 8
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 8.70 Å
5WYK Cryo-EM structure of the 90S small subunit pre-ribosome (Mtr4-depleted, Enp1-TAP) Deposited 2017-01-13 Assembly 1 Protein–RNA Heteromer；Protein × 55 PDB declaration: 58-meric（58） Consistent with all polymers
Chain P1 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 8
cryo-EM vitrification conditions Cryogen ETHANE；blot for 2 seconds before plunging
Resolution 4.50 Å
6EML Cryo-EM structure of a late pre-40S ribosomal subunit from Saccharomyces cerevisiae Deposited 2017-10-02 Assembly 1 Protein–RNA Heteromer；Protein × 31 PDB declaration: 31-meric（31） Consistent with protein count
Chain p 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.60 Å
6FAI Structure of a eukaryotic cytoplasmic pre-40S ribosomal subunit Deposited 2017-12-15 Assembly 1 Protein–RNA Heteromer；Protein × 35 PDB declaration: 36-meric（36） Consistent with all polymers
Chain h 1–274（274 aa）
Not recorded ZN ZINC ION × 2 MG MAGNESIUM ION × 46 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE-PROPANE
Resolution 3.40 Å
6RBD State 1 of yeast Tsr1-TAP Rps20-Deltaloop pre-40S particles Deposited 2019-04-10 Assembly 1 Protein–RNA Heteromer；Protein × 34 PDB declaration: 35-meric（35） Consistent with all polymers
Chain h 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE；blot 1.7-1.9 seconds before plunging
Resolution 3.47 Å
6Y7C Early cytoplasmic yeast pre-40S particle (purified with Tsr1 as bait) Deposited 2020-02-28 Assembly 1 Protein–RNA Heteromer；Protein × 33 PDB declaration: 34-meric（34） Consistent with all polymers
Chain h 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.80 Å
6ZQA Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state A (Poly-Ala) Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 57 PDB declaration: 60-meric（60） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 2 MG MAGNESIUM ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 4.40 Å
6ZQB Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state B2 Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 68 PDB declaration: 71-meric（71） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.90 Å
6ZQC Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state Pre-A1 Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 68 PDB declaration: 71-meric（71） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 2 MG MAGNESIUM ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.80 Å
6ZQD Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state Post-A1 Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 63 PDB declaration: 66-meric（66） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 MG MAGNESIUM ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.80 Å
6ZQE Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state Dis-A (Poly-Ala) Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 59 PDB declaration: 62-meric（62） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 2 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 7.10 Å
6ZQF Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state Dis-B (Poly-Ala) Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 39 PDB declaration: 42-meric（42） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 4.90 Å
6ZQG Cryo-EM structure of the 90S pre-ribosome from Saccharomyces cerevisiae, state Dis-C Deposited 2020-07-09 Assembly 1 Protein–RNA Heteromer；Protein × 34 PDB declaration: 37-meric（37） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 1 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 MG MAGNESIUM ION × 39 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.50 Å
7AJT Cryo-EM structure of the 90S-exosome super-complex (state Pre-A1-exosome) Deposited 2020-09-29 Assembly 1 Protein–RNA Heteromer；Protein × 79 PDB declaration: 83-meric（83） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 3 MG MAGNESIUM ION × 3 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 4.60 Å
7AJU Cryo-EM structure of the 90S-exosome super-complex (state Post-A1-exosome) Deposited 2020-09-29 Assembly 1 Protein–RNA Heteromer；Protein × 74 PDB declaration: 78-meric（78） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded ZN ZINC ION × 3 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 MG MAGNESIUM ION × 2 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.80 Å
7SUK Structure of Bfr2-Lcp5 Complex Observed in the Small Subunit Processome Isolated from R2TP-depleted Yeast Cells Deposited 2021-11-17 Assembly 1 Protein–RNA Heteromer；Protein × 67 PDB declaration: 70-meric（70） Consistent with all polymers
Chain SO 96–274（179 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.7
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.99 Å
7WTL Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Dis-D Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 18 PDB declaration: nonadecameric（19） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 MG MAGNESIUM ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.30 Å
7WTM Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Dis-E Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 16 PDB declaration: heptadecameric（17） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.50 Å
7WTN Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Tsr1-1 (with Rps2) Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 17 PDB declaration: octadecameric（18） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.40 Å
7WTO Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Tsr1-1 (without Rps2) Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 15 PDB declaration: hexadecameric（16） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.50 Å
7WTP Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Tsr1-2 (with Rps2) Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 18 PDB declaration: nonadecameric（19） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.80 Å
7WTQ Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Tsr1-2 (without Rps2) Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 17 PDB declaration: octadecameric（18） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.70 Å
7WTR Cryo-EM structure of a yeast pre-40S ribosomal subunit - State Tsr1-3 Deposited 2022-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 18 PDB declaration: nonadecameric（19） Consistent with all polymers
Chain CA 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.4
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.50 Å
8C00 Enp1TAP-S21_A population of yeast small ribosomal subunit precursors depleted of rpS21/eS21 Deposited 2022-12-15 Assembly 1 Protein–RNA Heteromer；Protein × 25 PDB declaration: 26-meric（26） Consistent with all polymers
Chain p 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 8
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 2.90 Å
8C01 Enp1TAP_A population of yeast small ribosomal subunit precursors Deposited 2022-12-15 Assembly 1 Protein–RNA Heteromer；Protein × 30 PDB declaration: 31-meric（31） Consistent with all polymers
Chain p 1–274（274 aa）
Not recorded ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 8
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 2.70 Å
9G33 Stalled 90S - Utp23-Krr1-deltaC3 Deposited 2024-07-11 Assembly 1 Protein–RNA Heteromer；Protein × 62 PDB declaration: 65-meric（65） Consistent with all polymers
Chain JJ 1–274（274 aa）
Not recorded GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.05 Å
9N6V SSU processome maturation and disassembly, State A Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 69 PDB declaration: 72-meric（72） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 25 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.16 Å
9N6W SSU processome maturation and disassembly, State A* Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 69 PDB declaration: 72-meric（72） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 25 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.05 Å
9N6X SSU processome maturation and disassembly, State B Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 69 PDB declaration: 72-meric（72） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 34 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.71 Å
9N6Y SSU processome maturation and disassembly, State C Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 70 PDB declaration: 73-meric（73） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 34 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.65 Å
9N6Z SSU processome maturation and disassembly, State D Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 69 PDB declaration: 72-meric（72） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 4.74 Å
9N70 SSU processome maturation and disassembly, State E Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 69 PDB declaration: 72-meric（72） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 5.17 Å
9N72 SSU processome maturation and disassembly, State F Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 70 PDB declaration: 73-meric（73） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 5.94 Å
9N73 SSU processome maturation and disassembly, State G Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 71 PDB declaration: 74-meric（74） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded No recorded non-water small molecule ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 5.96 Å
9N74 SSU processome maturation and disassembly, State H Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 68 PDB declaration: 71-meric（71） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 39 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 3 ADP ADENOSINE-5'-DIPHOSPHATE × 1 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 2.65 Å
9N75 SSU processome maturation and disassembly, State I Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 65 PDB declaration: 68-meric（68） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 59 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 3 ADP ADENOSINE-5'-DIPHOSPHATE × 1 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.01 Å
9N76 SSU processome maturation and disassembly, State J Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 64 PDB declaration: 67-meric（67） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 38 ATP ADENOSINE-5'-TRIPHOSPHATE × 1 ZN ZINC ION × 2 ADP ADENOSINE-5'-DIPHOSPHATE × 1 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 4.20 Å
9N77 SSU processome maturation and disassembly, State K Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 61 PDB declaration: 64-meric（64） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 48 ZN ZINC ION × 2 ADP ADENOSINE-5'-DIPHOSPHATE × 1 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.94 Å
9N78 SSU processome maturation and disassembly, State L Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 56 PDB declaration: 59-meric（59） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 47 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 4.17 Å
9N79 SSU processome maturation and disassembly, State M Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 42 PDB declaration: 45-meric（45） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 47 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.93 Å
9N7A SSU processome maturation and disassembly, State N Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 36 PDB declaration: 39-meric（39） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 47 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.84 Å
9N7B SSU processome maturation and disassembly, State O Deposited 2025-02-05 Assembly 1 Protein–RNA Heteromer；Protein × 34 PDB declaration: 37-meric（37） Consistent with all polymers
Chain SW 1–274（274 aa）
Not recorded MG MAGNESIUM ION × 47 ZN ZINC ION × 2 GTP GUANOSINE-5'-TRIPHOSPHATE × 1 ELECTRON MICROSCOPY
cryo-EM buffer pH 7.5
cryo-EM vitrification conditions Cryogen ETHANE
Resolution 3.25 Å

This page presents structural evidence recorded in PDB/mmCIF.“No recorded non-water small molecule” does not prove that the experimental sample was ligand-free; experimental conditions belong to the PDB experiment, while ligands and copy counts are shown for each biological assembly.