Endoplasmic reticulum membrane protein that promotes endoplasmic reticulum-associated endosome fission (PubMed:30220460). Localizes to contact sites between the endoplasmic reticulum and endosomes and acts by promoting recruitment of the endoplasmic reticulum to endosome tubules for fission (PubMed:30220460). Endosome membrane fission of early and late endosomes is essential to separate regions destined for lysosomal degradation from carriers to be recycled to the plasma membrane (PubMed:30220460). May form homodimers and heterodimers with TMCC2 or TMCC3 via the coiled-coil domains (PubMed:24454821). Interacts with ribosomal proteins RPL4 and RPS6 (PubMed:24454821). Specifically localizes to contact sites between the endoplasmic reticulum and endosomes that are spatially and temporally linked to endosome fission. Belongs to the TEX28 family.