Table 1. Mammalian FPK-2/FBPase-2 gene products.

All the mRNAs listed, except M and F, differ in terms of coding sequence. The M isoform is sometimes called the muscle isoenzyme. Only the mRNAs from gene 1 (formerly called gene A) are referred to in the literature as indicated. We propose here an ad hoc nomenclature for the other mRNAs. As gene 2 was called gene B, its transcripts were referred to earlier as B1 to B4. Some of the isoforms are coded by more mRNAs than indicated, due to transcription from several promoters and due to differential splicing with non-coding exons. See text for explanations and references.

Gene	Chromosome locus	Isoenzyme	mRNA	Isoform
PFKFB1	Human Xp11.21	Liver	L	L
	Rat Xq22-q31		M	M
			F	M
PFKFB2	Human 1q31	Heart	H1, H2, H4	Long (58 kDa)
	Rat 13		H3	Short (54 kDa)
PFKFB3	Human 10p14-p15	Brain/placenta	U	Ubiquitous
	Rat 17q12.3		I	Inducible
PFKFB4	Human 3p21-p22	Testis	T	T
	Rat 8q32