STRUCTURE AND DEVELOPMENTAL EXPRESSION OF MOUSE GARP, A GENE ENCODINGA NEW LEUCINE-RICH REPEAT-CONTAINING PROTEIN

Proteins with leucine-rich repeats (LRR) constitute a large family of molecules playing a role in protein-protein interactions and signal tr ansduction. They are involved in various cellular processes in differe nt species. We characterized the organization and pattern of expressio n of the mouse Garp gene. It is composed of two coding exons, expresse d as a major 4.3 kb mRNA, and encodes a putative LRR transmembrane pro tein with an extracellular region almost entirely made of 20 repeats, and a short intracytoplasmic region. The mouse GARP deduced amino-acid sequence is highly similar to that of the human protein. The Garp gen e is expressed in various areas in the mid-gestation developing embryo , including skin, lens fibre cells, nasal cavity, smooth and skeletal muscles, lung, and megakaryocytes of the fetal liver. In the adult it is expressed in the megakaryocytes of the spleen and in endothelial ce lls of the placenta. The data suggests that GARP might be involved in platelet-endothelium interactions.