Alternative titles; symbols
HGNC Approved Gene Symbol: SAA2
Cytogenetic location: 11p15.1 Genomic coordinates (GRCh38): 11:18,238,236-18,248,668 (from NCBI)
The acute phase reactant serum amyloid A (SAA) is a polymorphic apolipoprotein encoded by a family of highly homologous and closely linked genes (summary by Steel et al., 1993). For background information on SAA, see SAA1 (104750).
Dwulet et al. (1988) isolated from one individual 3 distinct serum amyloid A (SAA) proteins, each present in 2 forms (+/- the amino-terminal arginine), and fully sequenced them. The 6 sequences, referred to as SAA1, SAA1 des Arg, SAA2-alpha, SAA2-alpha des Arg, SAA2-beta, and SAA2-beta des Arg, are resolved by electrofocusing into 6 isoforms. SAA1 is the product of one gene, while SAA2-alpha and SAA2-beta, which differ by only a single amino acid, represent allelic sequences of a second gene. Although the first reported AA protein corresponded to SAA2-beta, subsequent analyses showed that the vast majority of the protein isolated from amyloid deposits is derived from SAA1 (104750). This gene product also represents the predominant SAA form isolated from or detected in the plasma of patients experiencing an acute phase response.
Sellar and Whitehead (1993) demonstrated that the SAA1, SAA2, and SAA3 genes, as well as a fourth gene, SAA4 (104752), are linked on 11p. There is strong evidence that SAA3 is a pseudogene (review by Steel et al., 1993). By fluorescence in situ hybridization using a cosmid probe containing the SAA2 and SAA4 genes, Sellar et al. (1994) localized these genes (and the closely situated SAA1 gene) to 11p15.1. Sellar et al. (1994) used an NcoI RFLP in the SAA2 gene to analyze for linkage in the CEPH reference panel. They found lod = 10.82 at theta = 0.001 for linkage between SAA3 and SAA2.
Kluve-Beckerman and Song (1995) showed that the SAA1 and SAA2 genes are arranged in a head-to-head transcriptional orientation about 18 kb apart. SAA4, the third functional serum amyloid locus, is 11 kb from SAA2 and in the same orientation.
Dwulet, F. E., Wallace, D. K., Benson, M. D. Amino acid structures of multiple forms of amyloid-related serum protein SAA from a single individual. Biochemistry 27: 1677-1682, 1988. [PubMed: 3130100] [Full Text: https://doi.org/10.1021/bi00405a044]
Kluve-Beckerman, B., Song, M. Genes encoding human serum amyloid A proteins SAA1 and SAA2 are located 18 kb apart in opposite transcriptional orientations. Gene 159: 289-290, 1995. [PubMed: 7622070] [Full Text: https://doi.org/10.1016/0378-1119(95)00027-4]
Sellar, G. C., Jordan, S. A., Bickmore, W. A., Fantes, J. A., van Heyningen, V., Whitehead, A. S. The human serum amyloid A protein (SAA) superfamily gene cluster: mapping to chromosome 11p15.1 by physical and genetic linkage analysis. Genomics 19: 221-227, 1994. [PubMed: 8188252] [Full Text: https://doi.org/10.1006/geno.1994.1051]
Sellar, G. C., Whitehead, A. S. Localization of four human serum amyloid A (SAA) protein superfamily genes to chromosome 11p: characterization of a fifth SAA-related gene sequence. Genomics 16: 774-776, 1993. [PubMed: 8325654] [Full Text: https://doi.org/10.1006/geno.1993.1265]
Steel, D. M., Sellar, G. C., Uhlar, C. M., Simon, S., DeBeer, F. C., Whitehead, A. S. A constitutively expressed serum amyloid A protein gene (SAA4) is closely linked to, and shares structural similarities with, an acute-phase serum amyloid A protein gene (SAA1). Genomics 16: 447-454, 1993. [PubMed: 7686132] [Full Text: https://doi.org/10.1006/geno.1993.1209]