Pleckstrin is a protein found in platelets. This name is derived from platelet and leukocyte C kinase substrate and the KSTR string of amino acids. Pleckstrin 2 contains two PH domains and a DEP (dishvelled, egl-10, and pleckstrin) domain. Unlike pleckstrin 1, pleckstrin 2 does not contain obvious sites of PKC phosphorylation. Pleckstrin 2 plays a role in actin rearrangement, large lamellipodia and peripheral ruffle formation, and may help orchestrate cytoskeletal arrangement. The PH domains of pleckstrin 2 are thought to contribute to lamellipodia formation. This cd contains the first PH domain repeat. PH domains have diverse functions, but in general are involved in targeting proteins to the appropriate cellular location or in the interaction with a binding partner. They share little sequence conservation, but all have a common fold, which is electrostatically polarized. Less than 10% of PH domains bind phosphoinositide phosphates (PIPs) with high affinity and specificity. PH domains are distinguished from other PIP-binding domains by their specific high-affinity binding to PIPs with two vicinal phosphate groups: PtdIns(3,4)P2, PtdIns(4,5)P2 or PtdIns(3,4,5)P3 which results in targeting some PH domain proteins to the plasma membrane. A few display strong specificity in lipid binding. Any specificity is usually determined by loop regions or insertions in the N-terminus of the domain, which are not conserved across all PH domains. PH domains are found in cellular signaling proteins such as serine/threonine kinase, tyrosine kinases, regulators of G-proteins, endocytotic GTPases, adaptors, as well as cytoskeletal associated molecules and in lipid associated enzymes.
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