Integrin alpha 7 as substrate for a glycosylphosphatidylinositol-anchored ADP-ribosyltransferase on the surface of skeletal muscle cells.
An arginine-specific mono-ADP-ribosyltransferase is expressed on the surface of differentiated mouse skeletal muscle cells and is anchored in the membrane via a glycosylphosphatidylinositol tail. Following incubation of intact cells with [adenylate-32P]NAD and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), a 97-kDa [32P]ADP-ribosylated protein was observed under reducing conditions and a 140-kDa complex under nonreducing conditions. The ADP-ribosylated protein was purified on a laminin affinity column. Based on its N-terminal sequence (FNLDVM-GAIRKEGEPGSLFGF) and a partial internal sequence (GLMRSEELSFVAGAP), the modified protein was identified as integrin alpha 7. Following partial trypsin digestion, a 39-kDa/79-kDa radiolabeled fragment was produced (reduced/nonreduced SDS-PAGE), narrowing the ADP-ribosylation site to a 39-kDa segment in the extracellular domain of integrin alpha 7. Labeling under optimal conditions was at least 0.4 mol of ADP-ribose/mol of integrin alpha 7. Selective expression of both ADP-ribosyltransferase and integrin alpha 7 in cardiac and skeletal muscle, a similar developmental appearance, and the apparently specific ADP-ribosylation, are consistent with a regulatory association between these proteins. ADP-ribosylation may modulate integrin receptor signaling and could play a significant role in the regulation of muscle cell function by the extracellular matrix.
Zolkiewska
A
A
Laboratory of Cellular Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
Moss
J
J
D036002:ADP Ribose Transferases; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D016023:Integrins / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D009132:Muscles / Q000201:enzymology / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry; D011065:Poly(ADP-ribose) Polymerases / Q000096:biosynthesis / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin
D017261:Glycosylphosphatidylinositols; D016023:Integrins; D008565:Membrane Proteins; D010446:Peptide Fragments; D036002:ADP Ribose Transferases; D011065:Poly(ADP-ribose) Polymerases; D014357:Trypsin