LAP2 binding protein 1 (L2BP1/BAF) is a candidate mediator of LAP2-chromatin interaction

Lamina-associated polypeptide (LAP) 2., which directly interacts with B-typ e lamins and chromosomes, is an integral membrane protein specifically dist ributed along the inner nuclear membrane of the nuclear envelope. The chrom atin- and lamin-binding activity of LAP2 suggests that LAP2 plays an import ant role in targeting mitotic vesicles to chromosomes and reorganizing the nuclear structure at the end of mitosis, Here I identified a LAP2 interacti ng protein, termed L2BP1 (LAP2 binding protein 1), The rat L2BP1 cDNA seque nce is predicted to encode a protein of 89 amino acids which turns out to b e a rat homolog of mouse and human BAF (Barrier-to-Autointegration Factor). L2BP1 is distributed diffusely throughout the nucleus in interphase cells. It is, however, highly concentrated at the chromosomes during the M-phase. Further, the L2BP1 binding domain of LAP2 overlaps its chromosome-binding region. These findings suggest that L2BP1 is a candidate mediator of LAP2-c hromosome interaction at the end of mitosis.