A new gene, BCM, on chromosome 16 is fused to the interleukin 2 gene by a t(4;16)(q26;p13) translocation in a malignant T cell lymphoma.
A t(4;16)(q26;p13.1) chromosome translocation found in tumour cells from a patient with a T cell lymphoma was shown to rearrange the interleukin 2 gene, normally located on chromosome band 4q26, with sequences from chromosome band 16p13.1. A cDNA library of tumour cells was screened with an interleukin 2 gene-specific probe. Three clones were isolated, which consisted, from 5' to 3', of the three first exons of the interleukin 2 gene followed by a 16p13 in-frame sequence encoding 181 amino acids. A probe derived from this sequence detected a 1.2 kb transcript in various cell lines exhibiting mature B lymphoid cell features, but this was not detected in other cell lines representative of other haematopoietic lineages, or in other organs. For this reason, the novel gene was termed BCM for B cell maturation. The open reading frame of BCM normal cDNA predicted a 184 amino acid protein with a single transmembrane domain which had no homology with any protein sequence stored in data banks. Our data indicate that BCM is a new gene whose expression coincides with B cell terminal maturation.