Molecular characterization of a type I serine-threonine kinase receptor for TGF-beta and activin in the rat pituitary tumor cell line GH3.
GH3 pituitary tumor cells have surface receptors for transforming growth factors-beta (TGF-beta s) and activins/inhibins. GH3 cell mRNA was screened by a novel reverse transcriptase-polymerase chain reaction technique with primers for receptor serine-threonine kinases. We isolated rat homologs of previously identified clones for type I (ALK-2 and ALK-5) and type II (ActRII, TGF-beta RII) activin and TGF-beta receptors, together with a novel clone, whose full-length version was isolated from a GH3 cell cDNA library. Named B1, it encodes a 505-amino-acid protein belonging to the family of type I receptor serine/threonine kinases. The kinase domain of B1 exhibits 90% identity to that of the TGF-beta type I receptor. B1 mRNA is expressed not only in pituitary cells but also in all other cells and tissues examined. B1 protein can be expressed on the cell surface, but cannot bind ligand unless a type II receptor is also present. When coexpressed with the type II receptors specific for TGF-beta or activin, B1 can be efficiently cross-linked to either ligand, suggesting that it can form heteromeric complexes with both type II receptor subunits.
Takumi
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T
Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142.
Moustakas
A
A
Lin
H Y
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Lodish
H F
HF
D029404:Activin Receptors; D028341:Activins; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D015870:Gene Expression; D007265:Inhibins / Q000378:metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017978:Receptors, Growth Factor / Q000235:genetics* / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D017978:Receptors, Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D011993:Recombinant Fusion Proteins; D016212:Transforming Growth Factor beta; D028341:Activins; D007265:Inhibins; D017346:Protein Serine-Threonine Kinases; D029404:Activin Receptors