Potential role in vesicular protein trafficking, mainly in the early secretory pathway. May act as a cargo receptor at the lumenal side for incorporation of secretory cargo molecules into transport vesicles and may be involved in vesicle coat formation at the cytoplasmic side. Plays a positive role in IL-33-mediated IL-8 and IL-6 production by interacting with interleukin-33 receptor IL1RL1 (PubMed:23319592). Also plays a role in the modulation of innate immune signaling through the cGAS-STING pathway by interacting with RNF26 (PubMed:32614325). {ECO:0000269|PubMed:23319592, ECO:0000269|PubMed:32614325}. This is the function of Ensembl gene identifier ENSG00000099203 (TMED1, transmembrane p24 trafficking protein 1).