Function
Transports glucuronic acid and free sialic acid out of the lysosome after it is cleaved from sialoglycoconjugates undergoing degradation, this is required for normal CNS myelination. Mediates aspartate and glutamate membrane potential-dependent uptake into synaptic vesicles and synaptic-like microvesicles. Also functions as an electrogenic 2NO(3)(-)/H(+) cotransporter in the plasma membrane of salivary gland acinar cells, mediating the physiological nitrate efflux, 25% of the circulating nitrate ions is typically removed and secreted in saliva.
Gene References into Functions
- study describes a novel pathogenic variant in SLC17A5, namely an intronic transposal insertion, in a patient with mild biochemical and clinical phenotypes. The presence of a small fraction of normal transcript may explain the mild phenotype. This case illustrates the importance of including lysosomal sialic acid storage disease in the differential diagnosis of developmental delay with postnatal onset and hypomyelination. PMID: 28187749
- Elevated levels of AST are Associated with Cardiovascular disease. PMID: 27872510
- These data demonstrate that sialin mediates nitrate influx into salivary gland and other cell types. PMID: 22778404
- the substrate-binding site of sialin (SLC17A5) PMID: 22334707
- Human SLC17A5 carrying mutations that causes both phenotypes of Salla disease and mutations that cause infantile sialic acid storage disease showed no transport activity PMID: 21781115
- analysis of crucial residues and substrate-induced conformational changes in SLC17 transporter sialin PMID: 20424173
- expression, localization, and targeting of the wild-type sialin, as well as two mutant polypeptides in sialic acid storage disorders PMID: 12359136
- In primary neuronal cultures sialin was not targeted into lysosomes but rather revealed a punctate staining along the neuronal processes and was also seen in the plasma membrane. PMID: 15006695
- Molecular studies showed that all four affected individuals were homozygous for the same novel 983G > A mutation in exon 8 of the SLC17A5 gene, replacing glycine with glutamic acid at position 328 of the sialin protein PMID: 15172005
- Two missense mutations and one small, in-frame deletion in sialin are associated with ISSD abolished transport, the mutation causing Salla disease (R39C) slowed down, but did not stop the transport cycle. PMID: 15510212
- there is a direct correlation between sialin function and the disease state of sialic acid storage disorders PMID: 15516337
- a SLC17A5 p.K136E mutation may have a role in a case of Italian severe Salla disease PMID: 16170568
- study assessed the effect of missense mutations in the sialin gene (G328E and G409E) and found complete loss of measurable transport activity with both and impaired trafficking of the G409E protein PMID: 17933575
- The lysosomal localization of human sialin was not or only partially affected by pathogenic missense mutations; in contrast, all pathogenic mutations abolished transport of sialic acid. PMID: 18399798
- sialin possesses dual physiological functions and acts as a vesicular aspartate/glutamate transporter PMID: 18695252
- Mutations in the SLC17A5 gene must be considered in two siblings with hypomyelination, even in the absence of sialuria. PMID: 19557856
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Involvement in disease
Salla disease (SD); Infantile sialic acid storage disorder (ISSD)
Subcellular Location
Cell membrane; Multi-pass membrane protein. Cytoplasmic vesicle, secretory vesicle, synaptic vesicle membrane; Multi-pass membrane protein. Lysosome membrane; Multi-pass membrane protein.
Protein Families
Major facilitator superfamily, Sodium/anion cotransporter family
Tissue Specificity
Found in fetal lung and small intestine, and at lower level in fetal skin and muscle. In the adult, detected in placenta, kidney and pancreas. Abundant in the endothelial cells of tumors from ovary, colon, breast and lung, but is not detected in endotheli
