Molecular cloning and sequence determination of four different cDNA species coding for alpha-subunits of G proteins from Xenopus laevis oocytes.
A cDNA library prepared from Xenopus laevis oocytes in lambda gt10 was screened with a mixture of three oligonucleotide probes designed to detect sequences found in different mammalian genes coding for alpha-subunits of G-proteins. In addition to a clone coding for a G alpha o-type subunit previously reported [(1989) FEBS Lett. 244, 188-192] four additional clones have been found coding for different G alpha protein subunits. By comparison with mammalian alpha-subunits, these oocyte cDNAs correspond to two closely related G alpha s-1a, to a G alpha i-1 and to a G alpha i-3 species. The derived amino acid sequences showed that both G alpha s species contain 379 residues, corresponding to the short species without the serine residue and with a calculated Mr of 42720. The G alpha i-1 gene encodes a 354 amino acid protein with an Mr of 39,000 and the G alpha i-3 encodes an incomplete open reading frame of 345 residues, lacking the first 9 amino acid residues at the NH2 terminus. All these G alpha-subunits showed high identity with their respective mammalian counterparts (75-80%), indicating a great degree of conservation through the evolution and the important cellular regulatory function that they play.
Olate
J
J
Departamento de Bioquímica, Facultad de Medicina, Universidad de Chile, Santiago.
Martinez
S
S
Purcell
P
P
Jorquera
H
H
Codina
J
J
Birnbaumer
L
L
Allende
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology; D014982:Xenopus laevis / Q000235:genetics*
D004247:DNA; D019204:GTP-Binding Proteins