Crystallization precursor scaffold

The ( X174 external scaffolding protein (protein D) performs many of the functions typically associated with internal species in one-scaffolding-protein systems the organization of assembly precursors into a procapsid and the stabilization of that structure. However, its function is physically and temporally dependent on the internal scaffolding protein, which induces the conformational changes in capsid pentamers to prevent their premature association. In the procapsid crystal structure, 20 D proteins are associated with each pentameric capsomer. Remarkably, there is little or no contact between capsid pentamers. The structure is primarily held together by 2-fold-related contacts between D proteins. 

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