The proteins in this family are represented by UNC-93 from Caenorhabditis elegans and also includes protein unc-93 homolog A (UNC93A), protein unc-93 homolog B1 (UNC93B1), and UNC93-like protein MFSD11 (also called major facilitator superfamily domain- containing protein 11 or protein ET). UNC-93 colocalizes with SUP-10 and SUP-9 within muscle cells. UNC-93 acts as a regulatory subunit of a multi-subunit potassium channel complex that may function in coordinating muscle contraction in C. elegans. UNC93B1 controls intracellular trafficking and transport of a subset of Toll-like receptors (TLRs), including TLR3, TLR7 and TLR9, from the endoplasmic reticulum to endolysosomes where they can engage pathogen nucleotides and activate signaling cascades. MFSD11 is ubiquitously expressed in the periphery and the central nervous system of mice, where it is expressed in excitatory and inhibitory mouse brain neurons.