Identification of MAL2, a novel member of the MAL proteolipid family, though interactions with TPD52-like proteins in the yeast two-hybrid system

The TPD52 (tumor protein D52)-like proteins are small coiled-coil motif-bea ring proteins which were first identified though their expression in human breast carcinoma. TPD52-like proteins are known to interact in hetero- and homomeric fashions, but there are no known heterologous binding partners fo r these proteins. We now report the cloning of a novel member of the MAL pr oteolipid family, named MAL2, though its interaction with a TPD52L2 bait in a yeast two-hybrid screen. MAL2 is predicted to be 176 residues (19 kDa) w ith four transmembrane domains and is 35.8% identical to MAL, a proteolipid required in apical vesicle transport. The MAL2 prey bound all TPD52-like b aits tested in the yeast two-hybrid system and in vitro translation of MAL2 produced a single 19-kDa S-35-labeled protein which specifically bound ful l-length GST-Tpd52 in GST pull-down assays. The gene MAL2, which was locali zed to human chromosomal band 8q23 and shown to consist of four exons, is p redominantly expressed in human kidney, lung, and liver. Our study has ther efore identified a novel member of the MAL proteolipid family and potential ly implicates TPD52-like proteins in vesicle transport.