This a domain found at the N-terminal of a family of proteins that includes FAM171A1/A2 and FAM171B. FAM171A1 is a type 1 transmembrane glycoprotein also known as astroprincin (APCN) due to abundant expression in astrocytes. APCN is also expressed in placental trophoblasts, skeletal and heart muscle, kidney and pancreas [1]. APCN is involved in the regulation of the cytoskeletal dynamics, playing a role in actin stress fiber formation.

1: Astroprincin (FAM171A1, C10orf38): A Regulator of Human Cell Shape and Invasive Growth. Rasila T, Saavalainen O, Attalla H, Lankila P, Haglund C, Holtta E, Andersson LC; Am J Pathol. 2019;189:177-189. PMID:30312582