Existence of multiple phosphorylated forms of human platelet actin binding protein.
Platelet actin binding protein (ABP) as isolated from human platelets exists in at least four phosphorylated forms which we have designated ABP-0, ABP-1, ABP-2, and ABP-3 whose phosphate content ranges from 18 (ABP-0) to 40 (ABP-3) moles Pi/mole ABP. These forms differ in their resistance to calpain cleavage and ability to cross-link F-actin with ABP-3 being the best in each of these properties. Attempts to phosphorylate ABP-1, two or three with protein kinase C (PKC) were unsuccessful except if the proteins were pretreated with Escherichia coli alkaline phosphatase. All of the forms could be phosphorylated with cAMP-dependent kinase (PKA) and subsequent resistance to calpain cleavage conferred. Phosphorylation/dephosphorylation of ABP may be an important regulatory mechanism by which the cytoskeletal architecture is stabilized or transformed.
Wu
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MP
Department of Biochemistry, State University of New York Health Science Center at Brooklyn 11203.
Jay
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Stracher
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D000199:Actins / Q000378:metabolism*; D001792:Blood Platelets / Q000201:enzymology*; D002154:Calpain; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism
D000199:Actins; D008840:Microfilament Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D002154:Calpain