Pulmonary surfactant-associated protein A1

In presence of calcium ions, it binds to surfactant phospholipids and contributes to lower the surface tension at the air-liquid interface in the alveoli of the mammalian lung and is essential for normal respiration. Enhances the expression of MYO18A/SP-R210 on alveolar macrophages (By similarity).; (Microbial infection) Recognition of M.tuberculosis by dendritic cells may occur partially via this molecule. Can recognize, bind, and opsonize pathogens to enhance their elimination by alveolar macrophages.; (Microbial infection) Binds M.pneumoniae CARDS toxin, serves as one receptor for this pathogen. When SFTPA1 is down-regulated by siRNA, less toxin binds to human cells and less vacuolization (a symptom of M.pneumoniae infection) is seen.