The GalR2 galanin receptor was originally cloned from the rat and consists of 372 amino acids, including three consensus sites for extracellular glycosylation, and several intracellular phosphorylation sites that differ from the GalRl receptor (Smith etal. 1997). The similarity between rat GalR2 and rat or human GalR3 is around 55-60 per cent, while the homology with the rat or human GalRl receptor is slightly lower, about 40 per cent. The human GalR2 receptor contains 387 amino acids, with a 15 amino acids shorter C-terminus (Bloomquist etal. 1998; Borowsky etal. 1998; Fathi etal. 1997).
The human GalR2 receptor gene is located on chromosome 17q25.3, and in mouse GalR2 has been mapped to chromosome 11 (Fathi et al. 1998a; Kolakowski et al. 1998; Pang et al. 1998). The exon/intron organization in the human GalR2 gene is different from the one observed in the GalR1 gene. The coding sequence in human GalR2 is encoded on two exons, separated by a 1.4 kb intron (Fathi et al. 1998a; Iismaa et al. 1998). Exon 1 encodes the NH2-terminal end and the first three TM domains, exon 2 encodes the remainder of the receptor, from intracellular loop 2 to the COOH-terminus. The rat GalR2 gene has been shown to have the same structure (Howard etal. 1997).
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