Binds to the Fc region of immunoglobulins alpha. Mediates several functions including cytokine production.

Tissue specificity;
Isoform A.1, isoform A.2 and isoform A.3 are differentially expressed between blood and mucosal myeloid cells. Isoform A.1, isoform A.2 and isoform A.3 are expressed in monocytes. Isoform A.1 and isoform A.2 are expressed in alveolar macrophages; however only one isoform is expressed at alveolar macrophages surfaces.