This cytoplasmic motif is highly similar to motifs found in the cytoplasmic region of DECTIN-1 and CLEC-2 which have been shown to be essential in DECTIN-1-mediated phagocytosis of Zymosan [38] and in CLEC-2-mediated platelet activation [39]. No significant sequence similarities were detected between lectin-like receptors and FLJ31166 or GABARAPL1 (data not shown). Moreover, these two genes do not share any common characteristics and do not appear to be evolutionary related. To reveal the evolutionary relationship between
the novel lectin-like receptors CLEC12B, CLEC9A and murine NKG2i and the other C-type lectin-like proteins encoded in the centromeric part of the NK gene complex, a phylogenetic tree including www.selleckchem.com/ferroptosis.html gene sequences of the NKG2 gene family was constructed selleckchem based on the amino acid sequences of the CTLD (Fig. 2B). As expected, the C-type lectin-like receptors clearly form two separate groups, namely the myeloid and NK receptor group, CLEC9A and CLEC12B clearly belonging to the myeloid subfamily. The tree furthermore shows that CLEC12B is most closely related to DECTIN-1. CLEC9A is similarly high
related to CLEC-1, DECTIN-1 and CLEC12B. mNKG2i on the other hand is most highly related to mNKG2e and is clearly a member of the NK receptor subfamily. Thus, the relationship displayed by the phylogenetic tree corresponds to the arrangement of the receptors in the NK gene complex. It is Molecular motor of interest to note that in the myeloid subgroup, the sequences of
the human receptors show highest homology to their murine homologues, whereas the human NKG2A, C and E receptors appear to show higher homology with each other than with the murine homologues, probably providing an example for convergent evolution of these three receptor chains. Expression of DECTIN-1, CLEC-1, CLEC-2 and LOX-1 has been thoroughly studied; therefore we focused on a comprehensive overview of the expression of only the recently identified genes CLEC12B and CLEC9A as well as FLJ31166 and Gabarapl1 in various cell lineages of haematopoietic origin. In clear contrast to the expression pattern of the already characterized receptors of the myeloid cluster, GABARAPL1 was found in all cell types tested (Fig. 3A), whereas expression of FLJ31166 could not be detected in any of the cells (data not shown). Expression of the C-type lectin-like gene CLEC9A was very low (<100 molecules/one million molecules of β2-microglobulin) in DC, HUVEC, the NK cell line NK-92, the monocytic cell line U-937 and the myeloid–erythroid line K-562. Expression was higher (>300 molecules/one million molecules of β2-microglobulin) in the B lymphoid line RPMI 8866, the B-lymphoblastoid line 721.221 and the T cell line Jurkat.