Calcium-dependent lectin involved in innate immune defense. Binds mannose, fucose and N-acetylglucosamine on different microorganisms and activates the lectin complement pathway. Binds to late apoptotic cells, as well as to apoptotic blebs and to necrotic cells, but not to early apoptotic cells, facilitating their uptake by macrophages (By similarity). Oligomeric complex of 3 or more homotrimers. Interacts with MASP1 and MASP2 (By similarity). Interacts with MEP1A and MEP1B and may inhibit their catalytic activity (By similarity). The coiled-coil domain mediates trimerization. Hydroxylation on proline residues within the sequence motif, GXPG, is most likely to be 4-hydroxy as this fits the requirement for 4-hydroxylation in vertebrates.