Structure and chromosomal location of mouse and human CD52 genes

Human CD52 (CAMPATH-1 antigen) is an abundant surface molecule on lymphocyt es and a favoured target for lymphoma therapy and immunosuppression. It com prises a small glycosylphosphatidylinositol (GPI) anchored peptide to which a large carbohydrate moiety is attached. Structurally similar proteins inc lude the proposed mouse homologue, B7 antigen (B7-Ag; not to be confused wi th the CD28 ligand), and human and mouse CD24. Sequence similarities betwee n CD52 and B7-Ag precursors are concentrated over the signal peptides and t he sequences cleaved during GPI attachment. While the short mature peptides are not apparently homologous, the N-linked glycosylation site is retained in both. We describe similarities in exon-intron organisation, syntenic ch romosome positions (human CD52, 1p36; mouse B7-Ag, chromosome 4, between Ds i1 and D4Nds16) and sequence homology in the promoter regions which strongl y suggests that B7-Ag is the mouse homologue of CD52. The structure of thes e genes is also similar to that of mouse CD24, suggesting a common ancestor . Promoter activities and transcription start sites were also analysed. The se results suggest that human CD52 and mouse B7-Ag gene expressions are con trolled by TATA-less promoters. (C) 1999 Elsevier Science B.V. All rights r eserved.