This is a domain found in the C-terminal region of STT3 present in P. furiosus. STT3 is an Oligosaccharyltransferase which catalyzes the transfer of a heptasaccharide, containing one hexouronate and two pentose residues, onto peptides in an Asn-X-Thr/Ser-motif-dependent manner. This domain, known as the Peripheral 2 (P2) domain, encircles the central core domain [1].

1: Structure-guided identification of a new catalytic motif of oligosaccharyltransferase. Igura M, Maita N, Kamishikiryo J, Yamada M, Obita T, Maenaka K, Kohda D; EMBO J. 2008;27:234-243. PMID:18046457