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Phosphorylation of an 85‐kd membrane protein by a novel mechanism.
Author(s) -
Seydel U.,
Huttner W. B.
Publication year - 1988
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1988.tb03312.x
Subject(s) - phosphorylation , dephosphorylation , biology , protein phosphorylation , phosphate , biochemistry , serine , membrane protein , nucleotide , phosphatase , membrane , protein kinase a , gene
Protein phosphorylation has been recognized as a major mechanism for the regulation of cellular functions. The classical phosphate donor in protein phosphorylation reactions is ATP. Here we show that 3′‐phosphoadenosine‐5′‐phosphosulphate (PAPS), a ubiquitous nucleotide so far known to have a central role in sulphate transfer, serves as phosphate donor for protein phosphorylation. In a very specific, rapid and probably autocatalytic reaction, the 3′‐phosphate group of PAPS was found to be transferred to a serine residue of an 85‐kd membrane protein (p85). ATP did not serve as phosphate donor in this reaction. Radioactive phosphate incorporated into p85 in a membrane fraction was rapidly lost by dephosphorylation after removal of PAPS or by exchange with unlabelled phosphate after addition of nonradioactive PAPS. PAPS‐dependent phosphorylation of the 85‐kd protein and other proteins was observed in all rat and bovine tissues examined, as well as in various mammalian cell lines. Our results indicate the existence of a novel widespread form of protein phosphorylation.