Summary of mutations and alterations identified in cDNA clones generated from B-CLL cell B29 mRNA species by RT-PCR. RT-PCR reactions were performed with 2 μg of cellular RNA from 6 selected B-CLL cell samples using two overlapping pairs of B29-specific primers (A). RT-PCR products were cloned and fully sequenced. A summary of the alterations detected in these B29 mRNA sequences and of their predicted consequences for B29 protein translation and function is shown (B). Two kinds of B29 mRNA clones (designated A and B) were detected in all B-CLL cell samples and are presumed to correspond to the products of B29 alleles. Numbering of the cDNA and amino acid sequences begins with the first base of the ATG methionine codon initiating translation. IG Domain denotes the B29 Ig-like domain. TM and CYTO denote the B29 transmembrane and cytoplasmic segments, respectively.