Basic Leucine Zipper Nuclear Factor 1 (BLZF1)

The deduced 400-amino acid protein has a calculated molecular mass of 45 kD. The N-terminal region of JEM1 is followed by a basic region containing a nuclear localization signal; a hinge region; a leucine zipper dimerization motif; and a C-terminal PEST motif. JEM1 also contains several phosphorylation sites. Northern blot analysis detected a 3.0-kb transcript in T-cell leukemia, pro-B, pre-B, myeloma, and plasmacytoma cell lines, but not in Burkitt lymphoma cells. Expression of JEM1 was also detected in several normal tissues, including adrenal gland. Epitope-tagged JEM1 was expressed in a punctate staining pattern in the nuclei of transfected COS-7 cells; it was excluded from nucleoli. SDS-PAGE of in vitro translated cDNA detected JEM1 at an apparent molecular mass of 42 kD.