Cloning and characterization of a novel ITIM containing lectin-like immunoreceptor LLIR and its two transmembrane region deletion variants.

A novel full-length cDNA was cloned from human dendritic cells (DC) by subtractive cloning and RACE. The deduced protein is a type II lectin-like membrane protein that contains an ITIM proximal to N terminal and is designated as lectin-like immunoreceptor (LLIR). The gene of LLIR is located in a region of chromosomal 12p13 and shows highest homologous with ASGPR. Two alternatively spliced transmembraneless variants of LLIR were identified by RT-PCR and named as LLIRv1 and LLIRv2. RT-PCR and immunoblotting analysis revealed that LLIR was expressed with much higher level in immature DC than in mature DC. The ITIM in LLIR was demonstrated to bind SHP-1 in HL-60 cell after the tyrosine had been phosphorylated. In addition, the mRNA expression level of LLIRv2 was raised when leukemia cells were induced to differentiate by PMA.