Additional products of the Tla locus of the mouse.

Abstract

Thymocytes and leukemia cells of some mouse strains yield TL proteins, precipitable by anti-TL antiserum and by anti-TL monoclonal antibodies, that include not only the familiar heavy (H) chain of 45-50 kDa but also products of higher molecular mass. Production of a 53-kDa TL form by TVc thymocytes was studied in detail. A cross was made between B1M.M (Tia) mice, which produce the 53-kDa TL, and mice of the A strain (Tlq4), which make only the usual H chain. Hemi-expression of apparently unaltered 53-kDa TL was observed in thymocytes of the Tlc"/Tlc" heterozygous F1 progeny. Thus, there was no indication of positive or negative trans interaction with respect to production of the 53-kDa TL form associated with Tia". We conclude that production of 53-kDa TL is governed intrachromospmally. Two-dimensional chymotryptic peptide maps of the TL H chain and the 53-kDa TL of TicV thymocytes differed only by added features found in the map of the 53-kDa TL. With the exception of Tic", all Tla alleles (TM6') yielded TL products of higher molecular weight than the accompanying H chain, although in the case of Tlab this was evident only in TL' leukemia cells because Toc thymocytes are TL-. For H-2, representing other class I genes, no products other than the familiar H chain were demonstrable under similar conditions.