Molecular cloning and expression pattern of porcine myeloid DAP12-associating lectin-1.

ABSTRACT

DAP12 is an ITAM-bearing membrane protein that is associated with activating receptors in natural killer cells, granulocytes, macrophages, and monocytes. Myeloid DAP12-associating lectin-1 (MDL-1) is a type II membrane protein that associates with DAP12. In this study, we report the molecular cloning of two isoforms of porcine MDL-1 cDNA from pulmonary alveolar macrophages. The porcine MDL-1 short form has 165 amino acids and 70% sequence identity with the mouse MDL-1 short form. The long form has 20 more amino acids in the stalk region and 71% sequence identity with human MDL-1 and 67% with the mouse MDL-1 long form. Porcine MDL-1 contains a conserved lysine in the transmembrane domain. There are six putative N-linked glycosylation sites in the MDL-1 long form. MDL-1 transcripts were detected exclusively in macrophages and monocytes by RT-PCR. When transfected into 293 cells, porcine MDL-1 is expressed on the cell surface associated with DAP12.