Fig. 1

Visual representation of putative structural and functional domains encoded by Sef (IL17RD) isoforms. The structure of Sef is comprised of an extracellular domain, a transmembrane domain and an intracellular domain which are delimited by the arrows. hSEF-a (IL17RD) contains a signal peptide sequence (residues 1–26) immediately upstream of the extracellular domain (residues 27–299). Within the extracellular domain are conserved domains, including an immunoglobulin-like domain (residues 89–126) and a fibronectin type III domain (residues 199–281). The extracellular domain is followed by a short transmembrane domain (residues 300–319). The intracellular domain (residues 320–739) contains a Sef/IL17R homology region (SEFIR) (residues 335–564) which contains a TRAF6 binding subdomain (residues 348–352) and a Toll/IL1R (TIR) subdomain (residues 355–508). The SEFIR domain is followed by a putative SH3 domain (residues 567–578) followed by a short cytoplasmic tail (residues 579–739). The conserved tyrosine 330 (Y330) and threonine 496 (T496) residues are indicated, and the three short sequence “boxes”, indicated as B1 for Box1 (residues 357–362), B2 for Box2 (residues 377–381) and B3 for Box3 (residues 500–503). hSEF-b is a cytosolic variant that lacks first 42 residues including the signal peptide, which are replaced by 10 new amino acids. hSEF-S is translated from an alternate initiation codon downstream of the hSEF-a initiation codon, and therefore lacks the signal peptide and immunoglobulin domain thus remaining in the cytoplasm