Phosphatase Subfamily STYXL1

Phosphatase Classification: Fold CC1: Superfamily CC1: Family DSP: Subfamily STYXL1

STYXL1 (MK-STYX) is pseudophosphatase (catalytically inactive).

Evolution

STYXL1 is found in metazoa but lost in ecdysozoa (arthropoda and nematoda). It is usually a copy per genome.

Domain

STYXL1 has two domains, N-terminal rhodanese domain and C-terminal the phosphatase domain.

Function

STYXL1 localizes to the mitochondria. STYXL1 is expressed in most tissues (see GTEx data).

STYXL1 physically and genetically interacts with the mitochondrial phosphatase PTPMT1, and suppresses PTPMT1 catalytic activity. STYXL1 knockdown induces robust chemoresistance to multiple cytotoxic death-inducing agents. Loss of STYXL1 blocks cytochrome c release, a critical and rate-limiting step in apoptosis. knockdown of PTPMT1 resensitizes STYXL1 knockdown cells to chemotherapeutics and restores the ability to release cytochrome c. Thus, a model has been proposed that MK-STYX controls apoptosis by negatively regulating PTPMT1 [1, 2].

STYXL1 also interacts with G3BP-1 (Ras-GTPase activating protein SH3 domain binding protein-1), a key component of stress granules. G3BP1 is an RNA-binding protein with endoribonuclease activity that is recruited to 'stress granules' after stress stimuli. Stress granules are large subcellular structures that serve as sites of mRNA sorting, in which untranslated mRNAs accumulate [3, 4].