Alternative splicing of CD79a (Ig-alpha/mb-1) and CD79b (Ig-beta/B29) RNA transcripts in human B cells.
The CD79a (Ig-alpha/mb-1) and CD79b (Ig-beta/B29) molecules form a membrane heterodimer that is non-covalently associated with surface membrane immunoglobulin and is the major signaling component of the B cell antigen receptor complex. We have defined variant RNA transcripts for both CD79a (Ig-alpha/mb-1) and CD79b (Ig-beta/B29) which appear to arise by alternative splicing. These splice variants are predicted to encode truncated forms of these molecules that result in the deletion of the entire extracellular Ig-like domain of CD79b and of a major portion of the extracellular domain of CD79a. The presence of these short transcripts in a variety of human B cells and B cell lines was established by an RNAse protection assay. The definition of these variant transcripts provides a basis for a continuing effort to define variant protein products of CD79a and CD79b and examine their role in B cell physiology.