a b Nordström KJ, Sällman Almén M, Edstam MM, Fredriksson R, Schiöth HB (September 2011). "Independent HHsearch, Needleman--Wunsch-based, and motif analyses reveal the overall hierarchy for most of the G protein-coupled receptor families". Molecular Biology and Evolution. 28 (9): 2471–80. doi: 10.1093/molbev/msr061. PMID 21402729.

a b c Bjarnadóttir TK, Gloriam DE, Hellstrand SH, Kristiansson H, Fredriksson R, Schiöth HB (September 2006). "Comprehensive repertoire and phylogenetic analysis of the G protein-coupled receptors in human and mouse". Genomics. 88 (3): 263–73. doi: 10.1016/j.ygeno.2006.04.001. PMID 16753280. The G protein-coupled receptor is activated by an external signal in the form of a ligand or other signal mediator. This creates a conformational change in the receptor, causing activation of a G protein. Further effect depends on the type of G protein. G proteins are subsequently inactivated by GTPase activating proteins, known as RGS proteins.Nguyen AH, Thomsen AR, Cahill TJ, Huang R, Huang LY, Marcink T, etal. (December 2019). "Structure of an endosomal signaling GPCR-G protein-β-arrestin megacomplex". Nature Structural & Molecular Biology. 26 (12): 1123–1131. doi: 10.1038/s41594-019-0330-y. PMC 7108872. PMID 31740855. The number 912 is very compact, and the ideal gearbox for cars with a short or open platform end, like tank cars or cabooses: Kim JY, Haastert PV, Devreotes PN (April 1996). "Social senses: G-protein-coupled receptor signaling pathways in Dictyostelium discoideum". Chemistry & Biology. 3 (4): 239–43. doi: 10.1016/S1074-5521(96)90103-9. PMID 8807851. peptide hormones (e.g., calcitonin, C5a anaphylatoxin, follicle-stimulating hormone [FSH], gonadotropin-releasing hormone [GnRH], neurokinin, thyrotropin-releasing hormone [TRH], and oxytocin);

CFR 49 section 232.2, includes the following stated requirements (expressed in terms of a drawbar) for prototype 1/1 railroad freight car coupler heights, including standard-gauge railroads in the United States that "... shall be 34 1/2 inches, and the minimum height of drawbars for freight cars on such standard-gauge railroads ... shall be 31 1/2 inches". The exact size of the GPCR superfamily is unknown, but at least 831 different human genes (or ~ 4% of the entire protein-coding genome) have been predicted to code for them from genome sequence analysis. [10] [11] Although numerous classification schemes have been proposed, the superfamily was classically divided into three main classes (A, B, and C) with no detectable shared sequence homology between classes. When a ligand binds to the GPCR it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF). The GPCR can then activate an associated G protein by exchanging the GDP bound to the G protein for a GTP. The G protein's α subunit, together with the bound GTP, can then dissociate from the β and γ subunits to further affect intracellular signaling proteins or target functional proteins directly depending on the α subunit type ( G αs, G αi/o, G αq/11, G α12/13). [6] :1160 As to mounting the #1 Gauge coupler from the 1907 kit on the GP40, it seems possible that some shortening of the loco's post and the pilot lip that protrudes could be trimmed off to obtain the proper coupler to rail head height. Since my original intent for designing the Datum Precision coupler box employing true Kadee centerset couplers was to avoid doing any cutting on the GP40, this would seem counterproductive. Royal Swedish Academy of Sciences (10 October 2012). "The Nobel Prize in Chemistry 2012 Robert J. Lefkowitz, Brian K. Kobilka" . Retrieved 10 October 2012.GPCRs downstream signals have been shown to possibly interact with integrin signals, such as FAK. [48] Integrin signaling will phosphorylate FAK, which can then decrease GPCR G αs activity. adenosine, bombesin, bradykinin, endothelin, γ-aminobutyric acid ( GABA), hepatocyte growth factor ( HGF), melanocortins, neuropeptide Y, opioid peptides, opsins, somatostatin, GH, tachykinins, members of the vasoactive intestinal peptide family, and vasopressin; G protein-coupled receptors are found only in eukaryotes, including yeast, and choanoflagellates. [4] The ligands that bind and activate these receptors include light-sensitive compounds, odors, pheromones, hormones, and neurotransmitters, and vary in size from small molecules to peptides to large proteins. G protein-coupled receptors are involved in many diseases. When the receptor is inactive, the GEF domain may be bound to an also inactive α-subunit of a heterotrimeric G-protein. These "G-proteins" are a trimer of α, β, and γ subunits (known as Gα, Gβ, and Gγ, respectively) that is rendered inactive when reversibly bound to Guanosine diphosphate (GDP) (or, alternatively, no guanine nucleotide) but active when bound to guanosine triphosphate (GTP). Upon receptor activation, the GEF domain, in turn, allosterically activates the G-protein by facilitating the exchange of a molecule of GDP for GTP at the G-protein's α-subunit. The cell maintains a 10:1 ratio of cytosolic GTP:GDP so exchange for GTP is ensured. At this point, the subunits of the G-protein dissociate from the receptor, as well as each other, to yield a Gα-GTP monomer and a tightly interacting Gβγ dimer, which are now free to modulate the activity of other intracellular proteins. The extent to which they may diffuse, however, is limited due to the palmitoylation of Gα and the presence of an isoprenoid moiety that has been covalently added to the C-termini of Gγ.