Biological Unit: Difference between revisions
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Of course, what is the functional form (biological unit) under one set of conditions may change under a different set of conditions, so there may be more than one functional form (biological unit) that includes a given protein chain. For example, phosphorylation or dephosphorylation by protein kinases or phosphatases often change the affinities between proteins, and hence their quaternary assemblies. | Of course, what is the functional form (biological unit) under one set of conditions may change under a different set of conditions, so there may be more than one functional form (biological unit) that includes a given protein chain. For example, phosphorylation or dephosphorylation by protein kinases or phosphatases often change the affinities between proteins, and hence their quaternary assemblies. | ||
Published macromolecular structure data files ([[Atomic coordinate files]], often in the [[PDB file format]]) contain the [[Asymmetric Unit]], which may be identical with the biological unit, or only a portion of it, or may contain multiple biological units. When publishing a macromolecular structure, the authors may elect to specify the biological unit. In the [[PDB file format]], this is done in REMARK 350. | Published macromolecular structure data files ([[Atomic coordinate files]], often in the [[PDB file format]]) contain the [[Asymmetric Unit]], which may be identical with the biological unit, or only a portion of it, or may contain multiple biological units. Interchain contacts that occur in the asymmetric unit that are absent in the biological unit are termed [[crystal contacts]]. When publishing a macromolecular structure, the authors may elect to specify the biological unit. In the [[PDB file format]], this is done in REMARK 350. | ||
==Examples== | ==Examples== | ||
