Enables IMP dehydrogenase activity. Involved in 'de novo' XMP biosynthetic process and GMP biosynthetic process. Acts upstream of or within lymphocyte proliferation and purine nucleotide biosynthetic process. Predicted to be located in cytosol and nucleus. Predicted to be active in cytoplasm. Is expressed in central nervous system and retina outer nuclear layer. Human ortholog(s) of this gene implicated in Leber congenital amaurosis 11; retinitis pigmentosa; and retinitis pigmentosa 10. Orthologous to human IMPDH1 (inosine monophosphate dehydrogenase 1). [provided by Alliance of Genome Resources, Apr 2022]