|Detection of CL‑P1/COLEC12 in J774A.1 Mouse Cell Line by Flow Cytometry. J774A.1 mouse reticulum cell sarcoma macrophage cell line was stained with Goat Anti-Mouse CL‑P1/COLEC12 APC‑conjugated Antigen Affinity-purified Polyclonal Antibody (Catalog # FAB3130A, filled histogram) or isotype control antibody (Catalog # IC108A, open histogram). View our protocol for Staining Membrane-associated Proteins.|
Collectins are a family of Ca++-dependent, C-type lectins that contain a collagenous domain and function as recognition molecules for molecular patterns found on pathogens (1‑4). Collectin Placenta 1 (CL-P1), also known as Collectin sub-family member 12 and Scavenger Receptor with C-type Lectin type I (SRCL), is a 140 kDa member of the collectin family of glycoproteins. With two exceptions, all collectins are secreted. CL-P1 is the only collectin known to be membrane bound, while CL‑L1 (Collectin Liver-1) is the only known cytoplasmic collectin (1). Mouse CL-P1 is synthesized as a 742 amino acid (aa) type II transmembrane glycoprotein that includes an N-terminal 39 aa cytoplasmic domain, an 18 aa transmembrane segment, and a 685 aa C-terminal extracellular domain. The short cytoplasmic domain contains an internalization motif (Y-K-R-F), while the ECD is complex, demonstrating a coiled-coil segment, a Ser-Thr rich region, a collagen-like structure, and a C‑type lectin/Carbohydrate Recognition Domain (CRD) (5, 6). Unlike human CL-P1, no splice variants of mouse CL-P1 have been described (5, 7). Trimerization of CL‑P1 is mediated by its collagen-like and coiled-coil helical domains (1, 6). Within the ECD, mouse CL-P1 shares 88%, 89%, 92%, and 98% aa sequence identity with bovine, canine, human, and rat CL-P1, respectively. The CRD shares 23‑27% aa sequence identity with the CRD of collectins CL-L1, collectin sub-family member 11, MBL, SP-A1, and SP-D. Notably, this CRD recognizes galactose and fucose within the context of asialo-orosomucoids associated with the Lewisx epitope (8, 9). CL‑P1 is expressed in vascular endothelial cells and may play a role in bacterial recognition or as a scavenger receptor for desialylated glycoproteins (6, 8).