Details

Autor(en) / Beteiligte

• Sullivan, Kathleen A.
• Liao, Yu-Chien
• Alborzi, Azadeh
• Beiderman, Barry
• Chang, Fu-Hsiung
• Masters, Susan B.
• Levinson, Arthur D.
• Bourne, Henry R.

Titel

Inhibitory and Stimulatory G Proteins of Adenylate Cyclase: cDNA and Amino Acid Sequences of the α Chains

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 1986-09, Vol.83 (18), p.6687-6691

Ort / Verlag

Washington, DC: National Academy of Sciences of the United States of America

Erscheinungsjahr

1986

Quelle

MEDLINE

Beschreibungen/Notizen

• The G protein family of signal transducers includes five heterotrimers, which are most clearly distinguished by their different α chains. The family includes Gs and Gi, the stimulatory and inhibitory GTP-binding regulators of adenylate cyclase; Go, a protein of unknown function abundant in brain; and transducin 1 and transducin 2, proteins involved in retinal phototransduction. Using a bovine α t1 cDNA as a hybridization probe, we have isolated mouse cDNAs that encode α chains of two G proteins. One encodes a polypeptide of 377 amino acids (Mr 43,856), identified as α s because it specifically fails to hybridize with any transcript in an α s-deficient S49 mouse lymphoma mutant, cyc-; the other encodes a polypeptide of 355 amino acids (Mr 40,482), presumed to be α i. These α chains and those of the retinal transducins exhibit impressive sequence homology. Of the four, α t1 and α t2 are most alike (81% identical amino acid residues), whereas the presumptive α i is more similar than α s to α t1 (63% vs. 38% identical residues). Sequence homologies with p21ras and elongation factor Tu identify regions of the α chains that form the site for GTP binding and hydrolysis. Further comparison of the α -chain sequences suggests additional regions that may contribute to interactions with β γ subunits and the receptor and effector components of different signal transduction systems.