Pyridoxal phosphate homeostasis protein (IPR011078)

Short name: PyrdxlP_homeostasis

Overlapping homologous superfamilies

Family relationships



Pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, is an essential cofactor for nearly 60 Escherichia coli enzymes and 140 human enzymes. It is a highly reactive molecule that is toxic in its free form. The E. coli PROSC, known as yggS, binds to PLP and is involved in PLP homeostasis, supplying this cofactor to apoenzymes while minimizing any toxic side reactions [PMID: 26872910, PMID: 27912044].

Proteins in this entry occur in archaea, bacteria and eukaryotes. The bacterial proteins are co-transcribed with proline biosysnthesis genes, hence this group of proteins are also named the proline synthetase co-transcribed homologues (PROSC) [PMID: 10496079].

The structure of the yeast protein (P38197) has been determined to a resolution of 2.0 A [PMID: 12499548]. Similar in structure to the N-terminal domains of alanine racemase and ornithine decarboxylase, it forms a TIM barrel fold which begins with a long N-terminal helix, rather than the classical beta strand found at the beginning of most other TIM barrels. Unlike alanine racemase and ornithine decarboxylase, which are two-domain dimeric proteins, the yeast protein is a single domain monomer. A pyridoxal 5'-phosphate cofactor is covalently bound towards the C-terminal end of the barrel, which is the usual active site in TIM-barrel folds. Some racemase activity was observed for this protein and it was suggested by the authors that it may function as a general racemase [PMID: 12499548].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0030170 pyridoxal phosphate binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns