Replacement of the alpha5 helix of Galpha16 with Galphas-specific sequences enhances promiscuity of Galpha16 toward Gs-coupled receptors.
G(16) can couple indiscriminately to a large number of G protein-coupled receptors (GPCRs), making it a prime candidate as a universal adaptor for GPCRs. In order to increase the promiscuity of Galpha(16), three chimeras incorporating increasing lengths of G(s)-specific residues (25, 44 or 81 residues) into the C-terminus of Galpha(16) were constructed and named 16s25, 16s44 and 16s81, respectively. The chimeras were examined for their ability to mediate receptor-induced stimulation of phospholipase C (PLC) and Ca(2+) mobilization. 16s25 was more effective than 16s44 and 16s81 at coupling to G(s)-linked receptors. 16s25 coupled productively to 10 different G(s)-coupled receptors examined and, for 50% of these receptors, 16s25-mediated PLC activities were higher than those mediated via Galpha(16). Similar results were observed for agonist-induced Ca(2+) mobilizations. These results show that incorporating the alpha5 helix of Galpha(s) into Galpha(16) can increase the promiscuity of 16s25 towards G(s)-coupled receptors.
Hazari
Anjali
A
Department of Biochemistry, the Biotechnology Research Institute, and the Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Lowes
Vicki
V
Chan
Jasmine H P
JH
Wong
Cecilia S S
CS
Ho
Maurice K C
MK
Wong
Yung H
YH
D000818:Animals; D001483:Base Sequence / Q000235:genetics; D019556:COS Cells; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D044385:GTP-Binding Protein alpha Subunits / Q000235:genetics / Q000378:metabolism*; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000235:genetics / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011943:Receptors, Adrenergic, beta / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D010738:Type C Phospholipases / Q000378:metabolism
D044385:GTP-Binding Protein alpha Subunits; D011943:Receptors, Adrenergic, beta; D043562:Receptors, G-Protein-Coupled; D011993:Recombinant Fusion Proteins; D010738:Type C Phospholipases; C112631:G protein alpha 16; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D019205:GTP-Binding Protein alpha Subunits, Gs; D020962:Heterotrimeric GTP-Binding Proteins; D002118:Calcium