The mannose 6-phosphate/insulin-like growth factor-II receptor is a substrate of type V transforming growth factor-beta receptor.
The type V transforming growth factor beta (TGF-beta) receptor (TbetaR-V) is a ligand-stimulated acidotropic Ser-specific protein kinase that recognizes a motif of SXE/S(P)/D. This motif is present in the cytoplasmic domain of the mannose 6-phosphate/insulin-like growth factor-II (Man-6-P/IGF-II) receptor. We have explored the possibility that the Man-6-P/IGF-II receptor is a substrate of TbetaR-V. Purified bovine Man-6-P/IGF-II receptor was phosphorylated by purified bovine TbetaR-V in the presence of [gamma-32P]ATP and MnCl2 with an apparent Km of 130 nM. TGF-beta stimulated the phosphorylation of the Man-6-P/IGF-II receptor at 0 degrees C in mouse L cells overexpressing the Man-6-P/IGF-II receptor and in wild-type mink lung epithelial (Mv1Lu cells) metabolically labeled with [32P]orthophosphate. The in vitro and in vivo phosphorylation of the Man-6-P/IGF-II receptor occurred at the putative phosphorylation sites as revealed by phosphopeptide mapping and amino acid sequence analysis. TGF-beta stimulated Man-6-P/IGF-II receptor-mediated uptake (approximately 2-fold after 12 h treatment) of exogenous beta-glucuronidase in Mv1Lu cells and type II TGF-beta receptor (TbetaR-II)-defective mutant cells (DR26 cells) but not in type I TGF-beta receptor (TbetaR-I)-defective mutant cells (R-1B cells) and human colorectal carcinoma cells (RII-37 cells) expressing TbetaR-I and TbetaR-II but lacking TbetaR-V. These results suggest the Man-6-P/IGF-II receptor serves as an in vitro and in vivo substrate of TbetaR-V and that both TbetaR-V and TbetaR-I may play a role in mediating the TGF-beta-stimulated uptake of exogenous beta-glucuronidase.
Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA.
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Huang
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008247:Lysosomes / Q000201:enzymology; D051379:Mice; D008907:Mink; D008969:Molecular Sequence Data; D019319:Okadaic Acid / Q000494:pharmacology; D010748:Phosphopeptides / Q000032:analysis; D010766:Phosphorylation; D017527:Receptor, IGF Type 2 / Q000235:genetics / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D013379:Substrate Specificity; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D010748:Phosphopeptides; D017527:Receptor, IGF Type 2; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D019319:Okadaic Acid; D005966:Glucuronidase