Involved in protein trafficking via association with clathrin and AP2 complex (By similarity). Upon bacterial lipopolysaccharide stimulation, mediates internalization of TLR4 to endosomes in dendritic cells and macrophages, and internalization of poly(I:C) to TLR3-positive endosomes in myeloid dendritic cells and epithelial cells; resulting in activation of TICAM1-mediated signaling and subsequent IFNB1 production (PubMed:27022195). Involved in T-cell antigen receptor-mediated signaling by regulating tyrosine kinase LCK localization, T-cell dependent antibody production and cytokine secretion (PubMed:19414744). May regulate B-cell antigen receptor-mediated signaling (By similarity). May play a pivotal role in the formation and/or maintenance of lipid rafts (By similarity). Interacts with TLR4; the interaction occurs in response to lipopolysaccharide stimulation. Interacts with CLTC; the interaction occurs in response to pathogens. Interacts with AP2A1 and AP2B1. Translocates from cytoplasm to cell membrane where it colocalizes with poly (I:C) and then moves to endosomes where it colocalizes with TLR3. Translocates from cytoplasm to cell membrane where it colocalizes with TLR4 and then together with TLR4 moves to endosomes, upon lipopolysaccharide stimulation (PubMed:27022195). Expressed in T-cells, B-cells, thymus and spleen (at protein level) (PubMed:19414744, PubMed:12805216). Expressed in dendritic cells, macrophages, heart, lung and small intestine (PubMed:19414744). Mutant mice have smaller spleen, fewer splenocytes, reduced IgM production and secrete less IFNG, during antigen re-stimulation (PubMed:19414744). Double RFTN1 and RFTN2 mutant mice show no visible phenotype under pathogen-free conditions but show greatly reduced IFNB1 production in splenic dendritic cells following poly(I:C) or LPS stimulation (PubMed:27022195). Belongs to the raftlin family.