Skip to main content

MTAP

Function

Catalyzes the reversible phosphorylation of S-methyl-5'-thioadenosine (MTA) to adenine and 5-methylthioribose-1-phosphate. Involved in the breakdown of MTA, a major by-product of polyamine biosynthesis. Responsible for the first step in the methionine salvage pathway after MTA has been generated from S-adenosylmethionine. Has broad substrate specificity with 6-aminopurine nucleosides as preferred substrates.

Involvement in disease

Diaphyseal medullary stenosis with malignant fibrous histiocytoma

DMSMFH

An autosomal dominant bone dysplasia characterized by pathologic fractures due to abnormal cortical growth and diaphyseal medullary stenosis. The fractures heal poorly, and there is progressive bowing of the lower extremities. Some patients show a limb-girdle myopathy, with muscle weakness and atrophy. Approximately 35% of affected individuals develop an aggressive form of bone sarcoma consistent with malignant fibrous histiocytoma or osteosarcoma.

None

The disease is caused by variants affecting the gene represented in this entry. DMSMFH causing mutations found in MTAP exon 9 result in exon skipping and dysregulated alternative splicing of all MTAP isoforms (PubMed:22464254).

Loss of MTAP activity may play a role in human cancer. MTAP loss has been reported in a number of cancers, including osteosarcoma, malignant melanoma and gastric cancer.

Pathway

Amino-acid biosynthesis; L-methionine biosynthesis via salvage pathway; S-methyl-5-thio-alpha-D-ribose 1-phosphate from S-methyl-5'-thioadenosine (phosphorylase route): step 1/1.

Sequence similarities

Belongs to the PNP/MTAP phosphorylase family. MTAP subfamily.

Tissue specificity

Ubiquitously expressed.

Cellular localization

  • Cytoplasm
  • Nucleus

Alternative names

  • S-methyl-5'-thioadenosine phosphorylase
  • 5'-methylthioadenosine phosphorylase
  • MTA phosphorylase
  • MTAP
  • MTAPase
  • MTAP
  • MSAP

Target type

Proteins

Molecular weight

31236Da