A genetic polymorphism in the constant region of rabbit b4 kappa chains.

Abstract

Much of what is known about the number and arrangement of genes encoding immunoglobulins, and the mechanisms involved in their selective expression, derives from studies involving allotypes. Rabbit allotypes have figured prominently in these studies particularly because they are found in almost every region of the immunoglobulin molecule. Amino acid sequence studies on rabbit allotypes of group a in the Vs region and group b in the C~ region have revealed an unusual degree of structural complexity within these allotypes in that many amino acid differences are found between alternative forms (1). For example, the b4 kappa-chain sequence differs in the constant region from that of the b9 kappa chain at approximately 33% of the positions (2). A further complexity of the rabbit C~ region is that b4 light chains from homogeneous antibodies differ from one another in certain positions (3, 4).The present report describes an inherited C~-region structural variant observed among L chains with the allotype b4. This variation of allotype b4 (b4var) 1 consists of two amino acid substitutions, at residues 121 and 124. The variation has been observed in five generations of a pedigreed family. Serologic analysis has revealed that b4 TM chains are indistinguishable with regard to their b4 allotype from those with the prototype b4 sequence. Use of this variant as a genetic marker can provide information concerning the number of genes encoding light-chain constant regions. Materials and MethodsRabbit 4539 (ala3/b4b4) underwent three immunization series with Group C streptococcal vaccine using methods previously described (5). During the third series, a monoclonal response was observed and three nonsurgical exchange transfusions (6) were carried out. A homogeneous antibody with allotype a3b4 (4539 Ab) was isolated from the transfusion plasma by DEAEcellulose chromatography and chromatography on a Group C carbohydrate immunoadsorbent column (7). Amino acid sequence studies on the light chain of 4539 Ab have been carried out using a strategy described elsewhere (8). Constant-region sequence variation was first observed upon sequence determination of a peptide (residues 110-207) isolated after acid cleavage (9) of the tryptic fragment encompassing residues 62-207.Analysis of rabbit sera for the presence of this variant sequence was carried out as follows: IgG, isolated by DEAE-cellulose chromatography, was mildly reduced and alkylated. Heavy and light

Genetic Characterization of a new allele of the rabbit group b Ck allotypes

“…Such bias was not found in the latest generation, which included barb 4v rabbits. Quantitative analysis for b4 v placed this allotype in the group b allotype 'pecking order' (Dubiski 1972) at approximately the same level as b5, a result consistent with quantitative sequence data for b4b4 v rabbits reported earlier (Sogn and Kindt 1976).…”

“…Chemical typing of b4 v was carried out as previously described (Sogn and Kindt 1976), by acid cleavage of mildly reduced and alkylated, succinylated L chains, followed by fifteen steps of automated Edman degradation using a Beckman Model 890C Sequencer. Two features of this assay procedure were examined in greater detail for the purposes of the present study.…”

“…A previous publication (Sogn and Kindt 1976) described an inherited sequence variant of b4, which was designated b4 TM 1. This trait was present in five generations i For reasons of simplicity the variant will be referred to here as b4 v 0093-7711/78/0007/0141/$01.40 142 J.A.…”

Nucleotide sequence of constant and 3' untranslated regions of a kappa immunoglobulin light chain mRNA of a homozygous b4 rabbit.

“…Sogn and Kindt have described a b4ar, which differs from the H sequence by two residues (35). Breeding studies suggest that H and b4ar could correspond to alternative forms of a H chain gene at a single genetic locus.…”

Structural studies on protein products of murine chromosome 17: partial amino acid sequence of an H-2Kb molecule.

“…The extraordinary number of differences in amino acid sequence between molecules bearing the various group a allotypic markers in the rabbit is well established. In addition, extensive sequence differences exist between b4, b6, and b9 constant regions of rabbit light chains (27)(28)(29)(30)(31). Recently, Gutman et al (32) have demonstrated that the kappa allotypes in the rat have multiple amino acid differences in the constant region.…”