This is the N-terminal domain of Ribitol-5-phosphate transferase FKTN (also referred to fukutin) which contains the transmembrane domain required for its localisation to the Golgi and participates in the interaction with POMGnT1 (Protein O-linked-mannose beta-1,2-N-acetylglucosaminyltransferase 1) for normal POMGnT1 location and activity []. FKTN is a ribitol-phosphate transferase that forms a complex with FKRP (fukutin-related protein, also a ribitol-phosphate transferase) and TMEM5 (a ribitol xylosyltransferase). Fukutin, FKRP, and TMEM5 maintain each of their enzyme activities in the complex and may contribute to specificbiosynthesis of glycans required for dystroglycan function [].
O-linked-mannose beta-1,2-N-acetylglucosaminyltransferase 1 (POMGnT1) participates in O-mannosyl glycosylation and may be responsible for creating GlcNAc(beta1-2)Man(alpha1-)O-Ser/Thr moieties on alpha dystroglycan and other O-mannosylated proteins [, ]. POMGnT1 consists of a stem domain, a catalytic domain, and an extended linker region connecting the two domains. The fold of the stem domain resembles that of PANDER (pancreatic-derived factor); a protein involved in the regulation of glucose homeostasis, but whose the molecular function has not been determined [].
This entry represents the ILEI/PANDER domain found in FAM3 family members and related proteins. Both PANDER and ILEI share a similar β-β-alpha fold, strikingly different from the classical cytokines [].FAM3C, also known as interleukin-like EMT inducer ILEI, is a secreted signaling protein involved in epithelial-mesenchymal transition and tumor progression [].FAM3B, also known as PANDER (PANcreatic DERived factor), is a cytokine-like protein that induces apoptosis of insulin-secreting beta-cells []and functions as a hormone by regulating glucose levels []. The fold of the stem domain of POMGnT1 (O-linked mannose beta1,2-N-acetylglucosaminyltransferase 1) resembles that of PANDER [].