Identification of three forms of the gamma subunit of G proteins isolated from bovine spleen.
We reported previously that G proteins from bovine spleen contain at least five forms of the gamma subunit (designated S1 through S5), among which S1 and S5 have been identified as novel gamma and gamma 2 subunits, respectively. In this study, we identified the other three forms of the gamma subunit, namely, S2, S3 and S4. Amino acid sequences of proteolytic fragments obtained from S2, S3 and S4 coincided exactly with internal sequences of gamma 7, gamma 5 and gamma 2, respectively. However, sequence analysis of undigested S4 revealed that S4 was an N-terminally truncated form of gamma 2, while analysis of the C-terminal fragment by fast atom bombardment mass spectrometry revealed that the C-terminus of S4 seemed to be geranylgeranylated and carboxymethylated as is that of intact gamma 2. Thus, the three types of gamma subunit obtained from bovine spleen were identified as gamma 7, gamma 5, and an N-terminally truncated gamma 2.
Morishita
R
R
Department of Biochemistry, Institute for Development Research, Aichi Prefectural Colony, Japan.
Masuda
K
K
Niwa
M
M
Kato
K
K
Asano
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013154:Spleen / Q000737:chemistry*
D010446:Peptide Fragments; D019204:GTP-Binding Proteins