Phosphorylation of an 85-kd membrane protein by a novel mechanism.
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.
Seydel
U
U
European Molecular Biology Laboratory, Heidelberg, FRG.
Huttner
W B
WB
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D006056:Golgi Apparatus / Q000378:metabolism; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D010724:Phosphoadenosine Phosphosulfate / Q000378:metabolism; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D012694:Serine / Q000378:metabolism
D008565:Membrane Proteins; D012694:Serine; D010724:Phosphoadenosine Phosphosulfate; D000255:Adenosine Triphosphate