5c79 | pdb_00005c79
PH domain of ASAP1 in complex with diC4-PtdIns(4,5)P2
Structural highlights
FunctionASAP1_MOUSE May function as a signal transduction protein involved in the differentiation of fibroblasts into adipocytes and possibly other cell types. Plays a role in ciliogenesis (By similarity). Posseses phosphatidylinositol 4,5-bisphosphate-dependent GTPase-activating protein activity for ARF1 (ADP ribosylation factor 1) and ARF5 and a lesser activity towards ARF6. May coordinate membrane trafficking with cell growth or actin cytoskeleton remodeling by binding to both SRC and PIP2. Publication Abstract from PubMedWe have defined the molecular basis for association of the PH domain of the Arf GAP ASAP1 with phospholipid bilayers. Structures of the unliganded and dibutyryl PtdIns(4,5)P2-bound PH domain were solved. PtdIns(4,5)P2 made contact with both a canonical site (C site) and an atypical site (A site). We hypothesized cooperative binding of PtdIns(4,5)P2 to the C site and a nonspecific anionic phospholipid to the A site. PtdIns(4,5)P2 dependence of binding to large unilamellar vesicles and GAP activity was sigmoidal, consistent with cooperative sites. In contrast, PtdIns(4,5)P2 binding to the PH domain of PLC delta1 was hyperbolic. Mutation of amino acids in either the C or A site resulted in decreased PtdIns(4,5)P2-dependent binding to vesicles and decreased GAP activity. The results support the idea of cooperative phospholipid binding to the C and A sites of the PH domain of ASAP1. We propose that the mechanism underlies rapid switching between active and inactive ASAP1. Molecular Basis for Cooperative Binding of Anionic Phospholipids to the PH Domain of the Arf GAP ASAP1.,Jian X, Tang WK, Zhai P, Roy NS, Luo R, Gruschus JM, Yohe ME, Chen PW, Li Y, Byrd RA, Xia D, Randazzo PA Structure. 2015 Sep 9. pii: S0969-2126(15)00335-4. doi:, 10.1016/j.str.2015.08.008. PMID:26365802[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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