This is a beta-hairpin domain found at the C-terminal region of astrotactin 2 proteins (ASTN-2). ASTN-2 is an integral membrane perforin-like protein linked to the planar cell polarity pathway in hair cells. it consists of multiple polypeptide folds: a perforin-like domain, a minimal epidermal growth factor-like module, a fibronectin type III domain Fn (III) and an annexin-like domain as well as the beta hairpin domain which packs across the fibronectin domain [1].

1: Structure of astrotactin-2: a conserved vertebrate-specific and perforin-like membrane protein involved in neuronal development. Ni T, Harlos K, Gilbert R; Open Biol. 2016; [Epub ahead of print] PMID:27249642