pfam19743: ASTN1_2_fn3 (This model is not part of the current CDD release)
ASTN1/2 Fn3 domain
Astrotactin-1 and 2 (ASTN1/2) are integral membrane proteins with a large C-terminal domain, extracellular for ASTN1 and endosome luminal for ASTN-2. They play critical roles in neurodevelopment, and ASTN-2 is also involved in the planar cell polarity pathway in hair cells. This is a domain found in the middle of the C-terminal of ASTN-1 and 2, which comprises a fibronectin type III (Fn(III)) domain. This domain located between the MACPF and annexin domains. The structure of Fn(III) from ASTN2 revealed an unexpected feature which has two additional beta strands folded across the core. The junction between EGF-4 and Fn(III) domains in ASTN2 (but not in ASTN1) is thought to be an inositol triphosphate binding site.
Jiyao W et al.(2023). "The conserved domain database in 2023.",