Activin receptors: cellular signalling by receptor serine kinases.
Activins are dimeric growth and differentiation factors which signal through a heteromeric complex of receptor serine kinases. Affinity labelling of activin-responsive cells with 125I-labelled activin A reveals activin-binding species of approximately 50 and 75 kDa, known as the type I and type II receptors, respectively. Molecular cloning has yielded genes encoding two type II receptors (ActRII and ActRIIB) and at least two type I receptors (ALK2 and ALK4). These receptors are members of a larger family of receptor serine kinases, which includes receptors for transforming growth factor beta (TGF beta), bone morphogenetic proteins and the Drosophila protein, decapentaplegic. Receptors I and II form a stable complex after ligand binding, resulting in phosphorylation of receptor I by receptor II. We have begun to identify intracellular targets of these molecules by using the intracellular domains of both ActRIs and ActRIIs as probes in the two-hybrid system, a cloning strategy designed to detect interacting proteins in yeast.
Zimmerman
C M
CM
Department of Biological Chemistry, University of Michigan, Ann Arbor 48109-0606, USA.
Mathews
L S
LS
D029404:Activin Receptors; D000818:Animals; D017173:Caenorhabditis elegans; D004330:Drosophila; D006367:HeLa Cells; D006801:Humans; D008956:Models, Chemical; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D017978:Receptors, Growth Factor / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D014982:Xenopus laevis
D017978:Receptors, Growth Factor; D017346:Protein Serine-Threonine Kinases; D029404:Activin Receptors