glyceraldehyde-3-phosphate dehydrogenase, type I. This model represents glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the enzyme responsible for the interconversion of 1,3-diphosphoglycerate and glyceraldehyde-3-phosphate, a central step in glycolysis and gluconeogenesis. Forms exist which utilize NAD (EC 1.2.1.12), NADP (EC 1.2.1.13) or either (1.2.1.59). In some species, NAD- and NADP- utilizing forms exist, generally being responsible for reactions in the anabolic and catabolic directions respectively. Two PFAM models cover the two functional domains of this protein; pfam00044 represents the N-terminal NAD(P)-binding domain and pfam02800 represents the C-terminal catalytic domain. An additional form of gap gene is found in gamma proteobacteria and is responsible for the conversion of erythrose-4-phosphate (E4P) to 4-phospho-erythronate in the biosynthesis of pyridoxine. This pathway of pyridoxine biosynthesis appears to be limited, however, to a relatively small number of bacterial species although it is prevalent among the gamma-proteobacteria. This enzyme is described by TIGR001532. These sequences generally score between trusted and noise to this GAPDH model due to the close evolutionary relationship. There exists the possiblity that some forms of GAPDH may be bifunctional and act on E4P in species which make pyridoxine and via hydroxythreonine and lack a separate E4PDH enzyme (for instance, the GAPDH from Bacillus stearothermophilus has been shown to posess a limited E4PD activity as well as a robust GAPDH activity). There are a great number of sequences in the databases which score between trusted and noise to this model, nearly all of them due to fragmentary sequences. It seems that study of this gene has been carried out in many species utilizing PCR probes which exclude the extreme ends of the consenses used to define this model. The noise level is set relative not to E4PD, but the next closest outliers, the class II GAPDH's (found in archaea, TIGR01546) and aspartate semialdehyde dehydrogenase (ASADH, TIGR01296) both of which have highest-scoring hits around -225 to the prior model [Energy metabolism, Glycolysis/gluconeogenesis].

Glyceraldehyde 3-phosphate dehydrogenase, NAD binding domain. GAPDH is a tetrameric NAD-binding enzyme involved in glycolysis and glyconeogenesis. N-terminal domain is a Rossmann NAD(P) binding fold.

Glyceraldehyde 3-phosphate dehydrogenase, NAD binding domain. GAPDH is a tetrameric NAD-binding enzyme involved in glycolysis and glyconeogenesis. N-terminal domain is a Rossmann NAD(P) binding fold.

glyceraldehyde-3-phosphate dehydrogenase

Exostosin family. The EXT family is a family of tumour suppressor genes. Mutations of EXT1 on 8q24.1, EXT2 on 11p11-13, and EXT3 on 19p have been associated with the autosomal dominant disorder known as hereditary multiple exostoses (HME). This is the most common known skeletal dysplasia. The chromosomal locations of other EXT genes suggest association with other forms of neoplasia. EXT1 and EXT2 have both been shown to encode a heparan sulphate polymerase with both D-glucuronyl (GlcA) and N-acetyl-D-glucosaminoglycan (GlcNAC) transferase activities. The nature of the defect in heparan sulphate biosynthesis in HME is unclear.