1bk2
A-SPECTRIN SH3 DOMAIN D48G MUTANT
Structural highlights
FunctionSPTN1_CHICK Morphologically, spectrin-like proteins appear to be related to spectrin, showing a flexible rod-like structure. They can bind actin but seem to differ in their calmodulin-binding activity. In nonerythroid tissues, spectrins, in association with some other proteins, may play an important role in membrane organization. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedWe have analyzed the existence of obligatory steps in the folding reaction of the alpha-spectrin SH3 domain by mutating Asp 48 (D48G), which is at position i+3 of an isolated two-residue type II' beta-turn. Calorimetry and X-ray analysis show an entropic stabilizing effect resulting from local changes at the dihedral angles of the beta-turn. Kinetic analysis of D48G shows that this beta-turn is fully formed in the transition state, while there is no evidence of its formation in an isolated fragment. Introduction of several mutations in the D48G protein reveals that the local stabilization has not significantly altered the transition state ensemble. All these results, together with previous analysis of other alpha-spectrin and src SH3 mutants, indicate that: (i) in the folding reaction there could be obligatory steps which are not necessarily part of the folding nucleus; (ii) transition state ensembles in beta-sheet proteins could be quite defined and conformationally restricted ('mechanic folding nucleus'); and (iii) transition state ensembles in some proteins could be evolutionarily conserved. Obligatory steps in protein folding and the conformational diversity of the transition state.,Martinez JC, Pisabarro MT, Serrano L Nat Struct Biol. 1998 Aug;5(8):721-9. PMID:9699637[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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