Orientational constraints of the gp130 intracellular juxtamembrane domain for signaling.
The glycoprotein 130 (gp130) is the common signal transducing receptor chain of the interleukin-6 family of cytokines. Here we investigated the requirements for transfer of the information given by ligand binding to the cytoplasmic domain of gp130. It is demonstrated that the box 1/2 region has to be located membrane-proximally in order to bind and activate Janus kinases. To test the possible requirement of an alpha-helical orientation, we inserted 1-4 alanine residues into this juxtamembrane intracellular region. The insertion of one alanine results in a strongly reduced activation of STAT1 and STAT3, whereas insertion of three alanine residues leads to a stronger STAT activation. These results suggest that gp130-mediated activation of STATs is sensitive to rotational changes around the receptor axis perpendicular to the membrane. Surprisingly, insertion of 1, 2, 3, or 4 alanine residues into this juxtamembrane region leads to successive impairment but not abolishment of Janus kinase and receptor phosphorylation, supporting the finding of sensitivity of Janus kinases toward changes in distance of box 1/2 from the plasma membrane. We suggest a new model concerning the gp130 activation mode in which the relative orientation of the cytoplasmic regions seems to be critical for further signal transduction.
Greiser
Jens S
JS
Institut für Biochemie, Universitätsklinikum der Rheinisch-Westfälischen Technischen Hochschule Aachen, Pauwelsstrasse 30, Aachen 52074, Germany.
Stross
Claudia
C
Heinrich
Peter C
PC
Behrmann
Iris
I
Hermanns
Heike M
HM
D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D016207:Cytokines / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D053613:Janus Kinase 1; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism
D016207:Cytokines; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015534:Trans-Activators; D011505:Protein-Tyrosine Kinases; D053613:Janus Kinase 1; D000409:Alanine