Pattern recognition receptor (PRR) which binds Gram-positive and Gram-negative bacteria (PubMed:9468508). Also plays a role in binding of unopsonized particles by alveolar macrophages (By similarity). Binds to the secretoglobin SCGB3A2 (PubMed:12847263). Homotrimer; disulfide-linked. Trimers may assemble in larger oligomers thus resulting in the creation of a large surface capable of interacting with very large ligands. Expressed in alveolar macrophages (at protein level). Detected in macrophages from various tissues including thymus, kidney, Kupffer cells of liver, and spleen (PubMed:9468508). N-glycosylated.