The alpha-subunits of G-proteins G12 and G13 are palmitoylated, but not amidically myristoylated.
The alpha-subunits of the G-proteins G12 and G13 were expressed with a baculovirus system in insect cells and analysed for acylation. Both proteins incorporated tritiated palmitic and to a lesser extent also tritiated myristic acid. Radiolabel from both fatty acids was sensitive to treatment with neutral hydroxylamine. This result supports a thioester-type fatty acid bond and argues against amidical N-myristoylation. Fatty acid analysis after labeling with [3H]palmitic acid showed that palmitate represents the predominant fatty acid linked to G alpha 12 and G alpha 13. Separation of cells into cytosolic and membranous fractions revealed that palmitoylated alpha-subunits of G12 were exclusively membrane-bound, whereas [35S]methionine-labeled proteins were detected in soluble and particulate fractions. Inhibition of protein synthesis with cycloheximide did not block palmitoylation of the alpha-subunits, which indicates that palmitoylation occurs independently of protein synthesis.
Veit
M
M
Institut für Immunologie und Molekularbiologie, Freie Universität Berlin, Germany.
Nürnberg
B
B
Spicher
K
K
Harteneck
C
C
Ponimaskin
E
E
Schultz
G
G
Schmidt
M F
MF
D000215:Acylation; D000595:Amino Acid Sequence; D000818:Animals; D016367:Baculoviridae / Q000235:genetics; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D015870:Gene Expression; D007163:Immunosorbent Techniques; D008969:Molecular Sequence Data; D009036:Moths; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D014162:Transfection; D014316:Tritium
D018076:DNA, Complementary; D009227:Myristic Acids; D010169:Palmitic Acids; D011994:Recombinant Proteins; D019814:Myristic Acid; D014316:Tritium; D019308:Palmitic Acid; D019204:GTP-Binding Proteins