Onco-developmentally regulated .alpha.-N-acetylgalactosaminyltransferase

Abstract

An onco-developmentally regulated .alpha.-N-acetylgalactosaminyltransferase is isolated as a component of a particulate membrane fraction separated from cell and tissue homogenates which has the following characeristics: (a) Activity in Various Cells and Tissues--present in human fetal lung fibroblasts, hepatoma tissues and placenta, but absent from normal adult liver, lung, kidney and spleen tissues; (b) Substrate Specificity--acts on polypeptides comprising a sequence of val-thr-his-pro-gly-tyr by catalyzing .alpha.-N-acetylgalactosaminylation at the thr residue of the sequence; (c) Requirements for Metal Ion--requires metal ion for activity in 25 mM tris buffer, pH 7.6; (d) Optimal pH--optimal pH is about 7.6 asssayed in hepatoma cell homogenate in tris buffer and at a pH of about 6 to about 7 assayed in hepatoma cell homogenate enzyme activity is higher in 2(N-morpholino)ethanelsulfonic acid than in cacodylate buffer; and (e) Km--apparent Km for UDP - GalNAc is about 48 .mu.m. The alpha-N-acetylgalactosaminyltransferase is used in a method of detecting tumor cells. Also, a diagnostic test kit for detecting tumor cells in a sample suspected of containing tumnor cells is disclosed containing as separate components: (a) labeled .alpha.-N-acetylgalactosamine; and (b) polypeptide substrate comprising a sequence of val-thr-his-pro-gly-tyr.

Dependencies are inferred from the claim text.