Organization of a functional chicken class II B gene.
Five class II (B-L) B genes are encoded in the major histocompatibility complex (MHC) of chickens of the B12 haplotype. We report here the nucleotide sequence of one of these genes, B-LBII, as well as the primary structure of a corresponding cDNA. The organization of B-LBII, its 5' flanking region including the promotor region, and the amino acid sequence of its product are compared to mammalian class II B genes and to the previously described B-LBIII gene, which probably is a pseudogene since no B-LBIII transcript could be identified. The 5' flanking region of B-LBII exhibits homologs of transcription-controlling sequence motifs, namely S, X, X2, and Y boxes, of class II A and B genes of rodents and man. However, the promotor region of B-LBIII lacks an equivalent of the S box, displays two nucleic acid substitutions in the core sequence of the Y box, and exhibits a 16 base pair (bp) deletion upstream of the site of initiation of transcription. Therefore, an aberrant promotor region is likely to account for the pseudogene-like nature of B-LBIII, which displays open-reading frames in all exons. The data obtained with the functional B-LBII gene are in line with our previous interpretation that both genomic organization and tertiary structure of class II beta molecules are remarkably conserved between birds and mammals.
Zoorob
R
R
Institut d'Embryologie Cellulaire et Moléculaire du CNRS, Nogent-sur-Marne, France.
Béhar
G
G
Kroemer
G
G
Auffray
C
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens / Q000235:genetics / Q000276:immunology*; D015698:Genomic Library; D006239:Haplotypes / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D008969:Molecular Sequence Data; D011061:Poly A / Q000235:genetics; D011544:Pseudogenes; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid
D000949:Histocompatibility Antigens Class II; C041136:Ia-like antigens, avian; D012333:RNA, Messenger; D011061:Poly A