B-cell variant of mouse T200 (Ly-5): evidence for alternative mRNA splicing.

The complete cDNA sequence of mouse T200 glycoprotein from the pre-B-cell line 70Z/3 has been determined. The deduced protein sequence differs from that previously reported for a T-cell form of the molecule [Saga, Y., Tung, J.-S., Shen, F.-W. & Boyse, E. A. (1986) Proc. Natl. Acad. Sci. USA 83, 6940-6944] by the insertion of 139 amino acid residues in the amino-terminal region of the molecule. RNA transfer blotting using a cDNA probe encoding this sequence established that the predominant T200 mRNA species from B cells and cytotoxic T-cell clones but not T-helper cell clones or thymocytes contain all or part of the insert. Overlapping genomic clones of murine T200 were isolated and analysis of the intron-exon structure at the 5' end of the gene provides evidence that variants of T200 glycoprotein are generated by alternative mRNA splicing.