Enables protein O-GlcNAc transferase activity. Involved in several processes, including circadian regulation of gene expression; positive regulation of cold-induced thermogenesis; and regulation of gluconeogenesis. Acts upstream of or within protein O-linked glycosylation. Predicted to be located in several cellular components, including euchromatin; neuronal cell body; and zymogen granule. Predicted to be part of histone acetyltransferase complex and protein N-acetylglucosaminyltransferase complex. Is expressed in several structures, including alimentary system; genitourinary system; nervous system; respiratory system; and sensory organ. Human ortholog(s) of this gene implicated in non-syndromic X-linked intellectual disability 106. Orthologous to human OGT (O-linked N-acetylglucosamine (GlcNAc) transferase). [provided by Alliance of Genome Resources, Apr 2022]