Functional analysis of B144/LST1: A gene in the tumor necrosis factor cluster that induces formation in eukaryotic cells

B144/LST1 is a gene encoded in the human major histocompatibility complex t hat produces multiple forms of alternatively spliced mRNA and encodes pepti des fewer than 100 amino acids in length. B144/LST1 is strongly expressed i n dendritic cells. Transfection of B144/LST1 into a variety of cells induce s morphologic changes including the production of long, thin filopodia diff ering from those seen on transfection of a dominant active CDC42 gene. The structures are dynamically rearranging and sometimes connect one cell with another. The full effect of B144/LST1 protein on cell morphology requires t he retention of at least one of the four cysteines of the peptide plus the presence of a hydrophobic segment in the protein, but requires only one of the two coding regions present in the terminal 3' exons. (C) 2001 Academic Press.