Immunoglobulin V H regions in Atlantic cod ( Gadus morhua L.): Their diversity and relationship to V H families from other species

Abstract

Variable regions (V H) of Atlantic cod cDNA clones have been isolated by the polymerase chain reaction (PCR) technique, using primers for the first constant domain of heavy chain (C H1) and λgt11. Based upon sequence analysis and comparisons these clones have been divided into three different V H families. The approximate number of members in each family was estimated by genomic Southern blot. Comparisons of complementarity determining regions (CDRs) and frameworks (FRs) show that FR2 and the last part of FR3 are the most conserved regions. The CDR3 is very heterogeneous and gives a major contribution to V H diversity. Possible relationships between V H sequences from 17 species are shown graphically. Different V H families are often more conserved between species than within any one species. Two genomic V H clones have been isolated and partially sequenced. The V H genes have an octamer and TATA motif in the 5′ region, followed by an 18-amino-acid-long hydrophobic leader, and the mature V H coding region. The characteristic heptamer-nonamer recombination signals for V H to D joining are present 3′ of the V H segment.