抄録
An arginine-specific ADP-ribosyltransferase activity was detected in chicken gizzard smooth muscle, and the specific activity is highest in the membrane fraction. This trans-ferase is released from the membrane fraction by phosphatidylinositol-specific phospho-lipase C (PI-PLC), suggesting that it is a glycosylphosphatidylinositol (GPI)-anchored protein. When primary cultured gizzard smooth muscle cells (SMCs) were incubated with [Eadenylate-32P]NAD, several proteins were labeled. The labeling was inhibited by preincubation of the cells with PI-PLC, or by the addition of 4-arginine to the reaction, and was sensitive to hydroxylamine treatment. The activity of the transferase was main-tained in differentiated SMCs cultured with insulin, but was dramatically decreased concomitantly with cell dedifferentiation induced by serum or a specific PI3-Itinase LY294002. These results indicate that the GPI-anchored arginine-specific ADP-ribosyltransferase is expressed on the surface of differentiated SMCs and can modify several cell surface proteins. Our results also suggest that PI3-kinase is involved in the regulation of transferase activity during differentiation.
