SLC25A22- solute carrier family 25 member 22, also known as Mitochondrial glutamate carrier 1 (GC1), is a mitochondrial glutamate/H+ symporter, responsible for the transport of glutamate from the cytosol into the mitochondrial matrix with the concomitant import of a proton¹. SLC25A22 mutations has been associate with colorectal cancer, osteosarcoma and neonatal myoclonic epilepsy². SLC25A22 was shown to be expressed in different tissues, especially in the brain, liver, and pancreas.

The mitochondrial carriers are a family of transport proteins in the inner membranes of mitochondria. They shuttle substrates, metabolites, and cofactors through this membrane and connect cytoplasm functions with others in the matrix. SLC25 is a large family of nuclear-encoded transporters embedded in the inner mitochondrial membrane and in a few cases other organelle membranes.
The two isoforms of the glutamate carrier GC1 and GC2 (encoded by SLC25A22 and SLC25A18, respectively) catalyze the transport of glutamate across the inner mitochondrial membrane, either by proton (H⁺) co-transport or in exchange for hydroxyl ions³ (OH^-).

SLC25A22 has a tumor-promoting function, promoting proliferation and migration of colorectal cancer cells with mutant KRAS, and formation and metastasis of colorectal cancer xenograft tumors in mice. Patients with colorectal tumors that express increased levels of SLC25A22 have shorter survival times than patients whose tumors have lower levels. SLC25A22 induces intracellular synthesis of aspartate, activation of mitogen-activated protein kinase and extracellular signal-regulated kinase signaling and reduces oxidative stress⁴.

SLC25A22 has been identified as the underlying cause of early myoclonic encephalopathy (EME) an electro-clinical epilepsy syndrome that manifests itself within the neonatal period or within the first 3 months of life. Genetic mapping of an autosomal recessive form of this condition to chromosome 11p15.5 and the identification of a missense mutation (p.Pro206Leu) in the gene encoding SLC25A22. The mutation cosegregated with the disease and altered a highly conserved amino acid, resulting in severe neonatal epilepsies with suppression-burst pattern³.