Two complementation classes of T200 (Ly-5) glycoprotein-negative mutants.

Mutants of murine lymphomas have been isolated which express less than 1 percent of wild-type levels of T200 (Ly-5) glycoprotein on their cell surface but express wild-type levels of other cell-surface antigens tested. These mutants define two genetic complementation classes. The Class A mutant does not synthesize detectable amounts of T200 glycoprotein and is a mutant in either the structural gene coding for the T200 glycoprotein or in a gene acting in cis position to regulate this structural gene. The Class B mutant synthesizes very low levels of T200 glycoprotein and is most simply interpreted as a mutant in a gene acting at some post-transcriptional step necessary for expression of the T200 glycoprotein on the cell surface.--The isolation of T200- mutants by cytotoxic immunoselection suggests that this method is a general way of studying the biosynthesis, regulation and function of cell-surface molecules.