1d1j
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CRYSTAL STRUCTURE OF HUMAN PROFILIN II
OverviewOverview
Human profilins are multifunctional, single-domain proteins which directly, link the actin microfilament system to a variety of signalling pathways, via two spatially distinct binding sites. Profilin binds to monomeric, actin in a 1:1 complex, catalyzes the exchange of the actin-bound, nucleotide and regulates actin filament barbed end assembly. Like SH3, domains, profilin has a surface-exposed aromatic patch which binds to, proline-rich peptides. Various multidomain proteins including members of, the Ena/VASP and formin families localize profilin:actin complexes through, profilin:poly-L-proline interactions to particular cytoskeletal locations, (e.g. focal adhesions, cleavage furrows). Humans express a basic (I) and, an acidic (II) isoform of profilin which exhibit different affinities for, peptides and proteins rich in proline residues. Here, we report the, crystallization and X-ray structure determination of human profilin II to, 2.2 A. This structure reveals an aromatic extension of the previously, defined poly-L-proline binding site for profilin I. In contrast to serine, 29 of profilin I, tyrosine 29 in profilin II is capable of forming an, additional stacking interaction and a hydrogen bond with poly-L-proline, which may account for the increased affinity of the second isoform for, proline-rich peptides. Differential isoform specificity for proline-rich, proteins may be attributed to the differences in charged and hydrophobic, residues in and proximal to the poly-L-proline binding site. The, actin-binding face remains nearly identical with the exception of five, amino acid differences. These observations are important for the, understanding of the functional and structural differences between these, two classes of profilin isoforms.
About this StructureAbout this Structure
1D1J is a Single protein structure of sequence from Homo sapiens with SO4, PG6 and PG5 as ligands. Full crystallographic information is available from OCA.
ReferenceReference
X-ray structure determination of human profilin II: A comparative structural analysis of human profilins., Nodelman IM, Bowman GD, Lindberg U, Schutt CE, J Mol Biol. 1999 Dec 17;294(5):1271-85. PMID:10600384
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