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

Abstract

Variable regions (VH) 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 (CH1) and lambda gt11. Based upon sequence analysis and comparisons these clones have been divided into three different VH 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 VH diversity. Possible relationships between VH sequences from 17 species are shown graphically. Different VH families are often more conserved between species than within any one species. Two genomic VH clones have been isolated and partially sequenced. The VH genes have an octamer and TATA motif in the 5' region, followed by an 18-amino-acid-long hydrophobic leader, and the mature VH coding region. The characteristics heptamer-nonamer recombination signals for VH to D joining are present 3' of the VH segment.