The erythropoietin receptor cytosolic juxtamembrane domain contains an essential, precisely oriented, hydrophobic motif.
We report that the erythropoietin receptor cytosolic juxtamembrane region is conformationally rigid and contains a hydrophobic motif, composed of residues L253, I257, and W258, that is crucial for Janus kinase 2 (JAK2) activation and receptor signaling. Alanine insertion mutagenesis shows that the orientation of this motif and not its distance from the membrane bilayer is critical. Intragenic complementation studies suggest that L253 is contained within an alpha helix functionally continuous to the transmembrane alpha helix. The alpha-helical orientation of L53 is required not for JAK2 activation but for activated JAK2 to induce phosphorylation of the erythropoietin receptor. This motif is highly conserved among cytokine receptors and couples ligand-induced conformational changes in the receptor to intracellular activation of JAK2.
Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA.
S N
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Constantinescu
L J
LJ
Huang
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H
Nam
H F
HF
Lodish
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D017124:Conserved Sequence; D019281:Dimerization; D004789:Enzyme Activation; D004921:Erythropoietin / Q000494:pharmacology; D005816:Genetic Complementation Test; D053614:Janus Kinase 2; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction
D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2