Table 2.

Intra- and intermolecular cross-linked peptides of membrane-associated Gt_α–GDP– AlF₄⁻ and Pγ

Cross-linked peptides were identified following chemical cross-linking of either lipobead-associated Gt_α–GDP–AlF₄⁻ or Gt_α–GDP–AlF₄⁻ incubated with a 2-fold stoichiometric excess of purified Pγ and analyzed as described under“Experimental procedures.” The abbreviations are defined in the legend to Table 1. All Gt_α intramolecular cross-links were detected in both the absence and the presence of Pγ.

Exp. m/z	z	Δ	pep1	aa1	pep2	aa2	Cross-linker
		ppm
451.2427	4	9.2	Gtα	16	Gtα	20	EDC
451.2424	4	−9.8	Gtα	16	Gtα	25	EDC
539.2929	3	−9.1	Gtα	17	Gtα	20	BS3
451.2498	4	6.6	Gtα	17	Gtα	21	EDC
487.2670	3	−9.4	Gtα	17	Gtα	22	EDC
723.7675	3	6.4	Gtα	17	Gtα	31	BS3
434.9019	3	−7.8	Gtα	18	Gtα	26	EDC
434.9022	3	−7.1	Gtα	18	Gtα	26	EDC
637.7287	3	−9	Gtα	18	Gtα	31	BS3
565.9201	5	−9.4	Gtα	18	Gtα	31	BS3
345.2063	4	3.3	Gtα	18	Gtα	267	BS3
899.8458	3	7.3	Gtα	20	Gtα	31	BS3
415.5742	3	−1.3	Gtα	20	Gtα	205	BS3
468.2516	3	−9.5	Gtα	21	Gtα	275	Sulfo-SDA
733.7522	3	−8	Gtα	24	Gtα	31	EDC
899.8322	3	−7.9	Gtα	25	Gtα	31	BS3
455.7341	4	−8.3	Gtα	25	Gtα	189	EDC
576.6672	3	−8.3	Gtα	26	Gtα	31	EDC
330.5199	3	−3.6	Gtα	26	Gtα	205	EDC
658.3810	3	−9.1	Gtα	39	Gtα	47	EDC
817.4389	4	−10	Gtα	169	Gtα	176	EDC
459.9397	3	4.2	Gtα	267	Gtα	275	DSS
446.2453	3	8	Gtα	267	Gtα	342	EDC
504.2656	2	−3	Gtα	98	Pγ	39	BS3
975.9864	2	−10	Gtα	129	Pγ	25	BS3
469.5794	3	7.2	Gtα	203	Pγ	39	BS3
440.9130	3	−10	Gtα	203	Pγ	45	BS3