title: Murine binding protein of the fourth component of complement: structural polymorphism and its linkage to the major histocompatibility complex.
abstract: The binding protein of the fourth component of complement (C4-BP) is a regulatory protein of the complement system with specific affinity for the fourth component. This paper describes a structural polymorphism of murine C4-BP and its linkage to the major histocompatibility complex of the mouse (H-2). After isoelectric focusing of whole mouse plasma in low-endosmosis agarose, C4-BP was demonstrated as a single precipitin band by overlaying monospecific antiserum on the agarose gel. Two C4-BP patterns were distinguished among many strains of mice on the basis of isoelectric point--C4-BP a type, which has a pH range of 6.5-7.0 (exemplified by B10.BR and B10.AKM), and C4-BP b type, which has a pH range of 6.3-6.6 (exemplified by B10 and B10.M). Genetic crosses between two strains bearing distinct C4-BP types demonstrate a C4-BP pattern representative of both types. A linkage study was carried out in which progeny of two backcross combinations--[(B10 X B10.BR)F1 X B10.BR] and [(B10.AKM X B10)F1 X B10.AKM]--were phenotyped for C4-BP type and serum fourth-component level. Results were obtained suggesting that C4-BP patterns are inherited by a single codominant locus (C4-Bp) linked to the H-2 complex. The recombination frequency between the C4-Bp locus and the S region was 0.017. By phenotyping appropriate intra-H-2 recombinants of three different backgrounds (B10, A, and HT), this locus was assigned to the right of the H-2D region.
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D050577:Complement C3-C5 Convertases / Q000235:genetics / Q000378:metabolism; D003181:Complement C4 / Q000235:genetics*; D005796:Genes; D008040:Genetic Linkage; D006183:H-2 Antigens / Q000235:genetics; D016167:Integrin alphaXbeta2; D008285:Major Histocompatibility Complex; D051379:Mice; D008815:Mice, Inbred Strains / Q000235:genetics; D011110:Polymorphism, Genetic; D013045:Species Specificity
chemical_list: D002352:Carrier Proteins; D003181:Complement C4; D006183:H-2 Antigens; D016167:Integrin alphaXbeta2; D050577:Complement C3-C5 Convertases