Open AccessPhosphorylation/dephosphorylation of the β light chain of clathrin from rat liver coated vesicles
Author(s) -
LOEB Jacques E.,
CANTOURNET Benoit,
VARTANIAN JeanPierre,
GORIS Jozef,
MERLEVEDE Wilfried
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb14817.x
Subject(s) - dephosphorylation , vesicle , clathrin , phosphorylation , immunoglobulin light chain , chemistry , microbiology and biotechnology , biophysics , biochemistry , biology , phosphatase , membrane , immunology , antibody
The phosphorylation in vitro , on serine residues by endogenous casein kinase 2, of the clathrin β light chain (33 kDa) of rat liver coated vesicles requires the presence of poly( l ‐lysine) which acts through binding to the β light chain. The phosphorylation of other proteins is also increased in the presence of poly( l ‐lysine) and casein kinase 2. In contrast, the phosphorylation of the upper band of the 50‐kDa protein doublet from rat liver coated vesicles is inhibited. Rat liver coated vesicles display a protein phosphatase activity which preferentially dephosphorylates clathrin β light chain. This activity is different from the protein phosphatase which dephosphorylates the 50‐kDa protein. This enzyme seems to be unrelated to the ATP/Mg‐dependent protein phosphatase, or the polycation‐stimulated protein phosphatases, which dephosphorylate the 50‐kDa protein and β light chain very efficiently, but with a different specificity. After dissociation of coated vesicles the β‐light‐chain phosphatase activity is recovered in the membrane fraction. This phosphatase activity is inhibited by 50 μM orthovanadate and 5 mM p ‐nitrophenyl phosphate but not by 10 mM EDTA.