title: Cloning and characterization of a transmembrane serine kinase that acts as an activin type I receptor.
abstract: Activin type II receptors are transmembrane protein-serine/threonine kinases. By using a reverse-transcription PCR assay to screen for protein kinase sequences, we isolated a cDNA clone, activin X1 receptor, from rat brain that encodes a 55-kDa transmembrane protein-serine kinase which is structurally related to other receptors in this kinase subfamily. The predicted protein consists of 509 amino acids, and the kinase domain shows 40% and 37% identity to the activin and transforming growth factor beta type II receptors, respectively. No activin-binding was observed when activin X1 receptor was expressed alone in COS-M6 cells; however, coexpression with type II activin receptors gave rise to a 68-kDa affinity-labeled complex in addition to the 85-kDa type II receptor complex. The size of this cross-linked band is consistent with the size of the type I activin receptor; furthermore, activin X1 receptor associated with type II receptors, as judged by coimmunoprecipitation with type II receptor antibodies. These data suggest that activin X1 receptor can serve as an activin type I receptor and that the diverse biological effects of activins may be mediated by a complex formed by the interaction of two transmembrane protein-serine kinases.
authors.affiliation: Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, CA 92037-1099.
authors.forename: K
authors.initials: K
authors.lastname: Tsuchida
authors.forename: L S
authors.initials: LS
authors.lastname: Mathews
authors.forename: W W
authors.initials: WW
authors.lastname: Vale
mesh_terms: D029404:Activin Receptors; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000235:genetics; D015870:Gene Expression; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011956:Receptors, Cell Surface / Q000235:genetics*; D017978:Receptors, Growth Factor / Q000235:genetics*; D018125:Receptors, Transforming Growth Factor beta / Q000737:chemistry; D014018:Tissue Distribution; D014162:Transfection
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D029404:Activin Receptors