Open AccessMyristoylation of the G alpha i2 polypeptide, a G protein alpha subunit, is required for its signaling and transformation functions.
Author(s) -
Carme Gallego,
Sunil Gupta,
Sim Winitz,
Bart Eisfelder,
Gary L. Johnson
Publication year - 1992
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.89.20.9695
Subject(s) - myristoylation , g alpha subunit , adenylyl cyclase , signal transduction , biology , microbiology and biotechnology , g protein , protein kinase a , gtp binding protein regulators , gs alpha subunit , alpha (finance) , protein kinase c , protein subunit , biochemistry , kinase , phosphorylation , medicine , construct validity , nursing , patient satisfaction , gene
GTPase-inhibiting mutations of the alpha subunit (alpha i2) of the G protein, Gi2, result in constitutive activation of alpha i2 signal transduction functions. GTPase-inhibited alpha i2 mutant polypeptides, referred to as gip2 oncoproteins, have glutamine-205 mutated to leucine (alpha i2Q205L). Expression of the alpha i2Q205L polypeptide inhibits adenylyl cyclase stimulation, constitutively activates p42 mitogen-activated protein kinase, and transforms Rat 1a fibroblasts. The alpha i2 polypeptides are N-terminal-myristoylated, but the function of myristoylation is unclear in alpha i2 signal transduction. We have tested the requirement for myristoylation on the ability of the alpha i2Q205L mutant polypeptide to constitutively regulate signal pathways and cell transformation. When expressed in Rat 1a cells, the nonmyristoylated alpha i2Q205L polypeptide is membrane associated but is unable to regulate adenylyl cyclase or p42 mitogen-activated protein kinase and does not induce cellular transformation. We conclude that myristoylation is absolutely necessary for alpha i2Q205L signal transduction and regulation of effector enzymes in the cell.