Characterization of transducin from bovine retinal rod outer segments. Participation of the amino-terminal region of T alpha in subunit interaction.

The carboxy-terminal domain of Gs alpha is necessary for anchorage of the activated form in the plasma membrane.

“…In this context, the amino-terminal deletion in (A2-29)Gsot would mimic the amino-terminal cleavage by V8 protease in Gsot. If we take into account the apparent size decrease between uncleaved Gsot (46 kD) and the membrane-bound 44-kD V8 protease fragment, the immunoprecipitation of the 44-kD fragment by the NH2-terminal antiserum and the location of the V8 protease site in Tct (20), Glu 27 represents the most probable, albeit speculative, location for the aminoterminal site.…”

“…Gsot was notably divergent in the 25 carboxyterminal residues (2,4,8,11). For example, divergence be-tween the carboxy-terminus of Gsot and that of Tot is exemplified by the absence of the carboxy-terminal V8 site in Tot (20). Therefore, it is less surprising that the domain required for anchorage of the activated ot subunit may be located in the carboxy-terminal residues for Gsot instead of the aminoterminal residues as suggested for Goot or Giot (5,12,19).…”

Amino- and carboxy-terminal deletion mutants of Gs alpha are localized to the particulate fraction of transfected COS cells.

“…The nucleotide sequence coding for 26 amino acid residues from Cys-3 to Lys-28 was deleted from the cDNA of rat Gsct-1 to construct (A3-28)Gso~-1, and the cDNA was cloned into the pCD-PS vector for transfection into COS-7 cells. We chose to delete this portion of Gsa since the amino terminus has been implicated in a subunit membrane binding and interaction with the/~/3' complex (20,28,29). The cells transfected with pCD-(A3-28)Gsot-1 exhibited a new band, which was resolved narrowly from the 42-kD protein and detected only with the carboxy terminal antibody, RM, but not with amino terminal antibody, GCL.…”

Roles of Lipid Modifications of Transducin Subunits in Their GDP-Dependent Association and Membrane Binding

“…The a subunits are generally N-myristoylated on glycine 2, after cleavage of the initial methionine, and/or palmitoylated on cysteine 3 (Linder et al, 1991(Linder et al, , 1993. The amino terminus sequences of the a subunits are critical for their interaction with Gfiy (Navon & Fung, 1987;Neer et al, 1988;Joumot et al, 1991a) and for their membrane attachment (Joumot et al, 1991b), which is most likely due to the attached acyl chain (Kokame et al, 1992). The Gfiy subunits are prenylated, with a C15 famesyl or a C20 geranylgeranyl chain T This work was supported by a grant from the Human Frontier Science Program.…”