C1orf25, also known as TRM1L (TRMT1-like protein), MST070 or MSTP070, is a 733 amino acid protein that belongs to the TRM1 family of proteins. Expressed in a wide variety of tissues, C1orf25 contains one C2H2-type zinc finger and shares sequence similarity with TRMT1, a tRNA methyltransferase that dimethylates guanine at position 26 of tRNAs. As is suggested by observations of C1orf25-deficient mice, C1orf25 is believed to play a role in exploratory behavior and motor coordination. The gene encoding C1orf25 localizes to chromosome 1 and, due to alternative splicing events, C1orf25 exists as at least two isoforms.