Myoblast-specific protein that mediates myoblast fusion, an essential step for the formation of multi-nucleated muscle fibers (PubMed:28681861). Actively participates in the membrane fusion reaction by mediating the mixing of cell membrane lipids (hemifusion) upstream of MYMX. Acts independently of MYMX (By similarity). Involved in skeletal muscle regeneration in response to injury by mediating the fusion of satellite cells, a population of muscle stem cells, with injured myofibers (By similarity). Also involved in skeletal muscle hypertrophy, probably by mediating the fusion of satellite cells with myofibers (By similarity). Interacts with MYMX. Localizes on the plasma membrane of myoblasts, where it mediates myoblasts fusion. Also localizes in the Golgi apparatus and post-Golgi following palmitoylation; the role of Golgi localization is unclear. Palmitoylated at the C-terminus; palmitoylation promotes localization to the Golgi apparatus. The disease is caused by variants affecting the gene represented in this entry. Belongs to the TMEM8 family.