This family comprises IL17 receptors (IL17Rs, e.g. Swiss:Q60943) and SEF proteins (e.g. Swiss:Q8QHJ9). The latter are feedback inhibitors of FGF signalling and are also thought to be receptors. Due to its similarity to the TIR domain (Pfam:PF01582), the SEFIR region is thought to be involved in homotypic interactions with other SEFIR/TIR-domain-containing proteins. Thus, SEFs and IL17Rs may be involved in TOLL/IL1R-like signalling pathways [1].

1: The STIR-domain superfamily in signal transduction, development and immunity. Novatchkova M, Leibbrandt A, Werzowa J, Neubuser A, Eisenhaber F; Trends Biochem Sci 2003;28:226-229. PMID:12765832

2: Evolution of prokaryotic homologues of the eukaryotic SEFIR protein domain. Wu B, Gong J, Liu L, Li T, Wei T, Bai Z; Gene. 2011; [Epub ahead of print] PMID:22037611