Isolation of novel complementary DNA clones from T lymphoma cells: one encodes a putative multiple membrane-spanning protein

Five novel complementary DNA (cDNA) clones which are differentially expressed between two closely related T lymphoma cell clones were isolated using subtradion-enriched differential screening. 511 2.4 cells, from which the cDNAs were isolated, have charaderistics of thymocytes at an intermediate stage in development and cause prominent extranodal ovarian tumors in syngeneic animals. A sister cell clone, SL12.3, derived from the same tumor, has a distind phenotype and causes more aggressive, diffuse lymphomas. Four of the five novel genes are expressed in normal thymus, adivated spleen cells, or gut-associated lymphoid tissue. The DNA sequence and predided protein sequence are presented for one of the novel cDNA clones. This novel cDNA clone deteds mRNA in normal thymus, gut-associated lymphoid tissue, and ovarian tissue. The predided protein has four putative transmembrane-spanning regions. The expression of the transcript is repressed in somatic cell hybrids formed from 5L12.4 cells fused with three different T lymphoma cell lines which lack detedable mRNA complementary to the novel cDNA clone. This trans-negative regulation suggests that the expression of the gene is regulated by repressional mechanisms.