3ub5 | pdb_00003ub5
Profilin:actin with a wide open nucleotide cleft
Structural highlights
Function[ACTB_BOVIN] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells. [PROF1_BOVIN] Binds to actin and affects the structure of the cytoskeleton. At high concentrations, profilin prevents the polymerization of actin, whereas it enhances it at low concentrations. By binding to PIP2, it inhibits the formation of IP3 and DG. Inhibits androgen receptor (AR) and HTT aggregation and binding of G-actin is essential for its inhibition of AR (By similarity). Publication Abstract from PubMedActin is a ubiquitous eukaryotic protein that is responsible for cellular scaffolding, motility, and division. The ability of actin to form a helical filament is the driving force behind these cellular activities. Formation of a filament depends on the successful exchange of actin's ADP for ATP. Mammalian profilin is a small actin binding protein that catalyzes the exchange of nucleotide and facilitates the addition of an actin monomer to a growing filament. Here, crystal structures of profilin-actin have been determined to show an actively exchanging ATP. Structural analysis shows how the binding of profilin to the barbed end of actin causes a rotation of the small domain relative to the large domain. This conformational change is propagated to the ATP site and causes a shift in nucleotide loops, which in turn causes a repositioning of Ca(2+) to its canonical position as the cleft closes around ATP. Reversal of the solvent exposure of Trp356 is also involved in cleft closure. In addition, secondary calcium binding sites were identified. Structural basis for profilin-mediated actin nucleotide exchange.,Porta JC, Borgstahl GE J Mol Biol. 2012 Apr 20;418(1-2):103-16. Epub 2012 Feb 22. PMID:22366544[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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