Phosphorylation Characteristics of Brain Clathrin‐Coated Vesicle Endogenous Proteins

William J. Schook, Carlo Parker, Walter I. Silva, D. Stave Kohtz, Saul Puszkin

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4 Scopus citations


Clathrin‐coated vesicles purified from bovine brain express protein kinase activity on two principal endogenous vesicle‐associated substrates: a 50,000‐Mr poly‐peptide (pp50) and clathrin‐associated protein2 (CAP2; the faster‐migrating clathrin light chain). Various exogenous substrates, e.g., casein, phosvitin, histone II, and histone III, also are phosphorylated. The pp50 protein kinase activity of clathrin‐coated vesicles is not modulated by Ca2+, calmodulin, phosphatidylserine, or cyclic AMP. On the other hand, phosphorylation of the other endogenous substrates requires certain activators, including histone, polylysine, polyarginine, or polyethylenimine. Phosphate incorporation into pp50 was sensitive to divalent cations that inhibit sulfhydryl‐dependent enzymes in the following order of potency: Zn2+ > Hg2+ > Cd2+, Cu2+, and Pb2+. Phosphate incorporation into CAP2 with polylysine present was insensitive to divalent cations. The alkylating agents dithiodini‐trobenzene, phenacyl bromide, and N‐ethylmaleimide inhibited phosphate incorporation into pp50 up to 90% without affecting incorporation into the other substrates. Vanadium pentoxide inhibited phosphorylation of CAP2 but had a minimal effect on pp50. CAP2 kinase activity was separated from the coated vesicle membrane and from disassembled clathrin triskelions, coeluting with the assembly polypeptide complex on a Sepharose 4B column. It retained phosphorylation properties similar to those of intact vesicles. These data imply that clathrin‐coated vesicle kinases are elements of the coat proteins and may be involved in the assembly/disassembly of clathrin triskelions or interactions of coated vesicles with other cellular components.

Original languageEnglish
Pages (from-to)434-441
Number of pages8
JournalJournal of Neurochemistry
Issue number2
StatePublished - Aug 1987


  • Clathrin triskelions
  • Clathrin‐associated protein
  • Clathrin‐coated vesicles
  • Coat proteins
  • Phosphorylation
  • Protein kinase activity


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