Enables geranyltranstransferase activity. Involved in several processes, including farnesyl diphosphate biosynthetic process; positive regulation of cell growth involved in cardiac muscle cell development; and positive regulation of cholesterol biosynthetic process. Located in mitochondrial matrix and peroxisome. Human ortholog(s) of this gene implicated in porokeratosis. Orthologous to human FDPS (farnesyl diphosphate synthase). [provided by Alliance of Genome Resources, Apr 2022]