Cystatin C
| Cystatin C | ||
|---|---|---|
|
||
| according to PDB 1R4C | ||
|
Existing structural data: 1g96, 1r4c, 1tij |
||
| Properties of human protein | ||
| Mass / length primary structure | 120 aa; 13.26 kDa | |
| Secondary to quaternary structure | Homodimer | |
| Identifier | ||
| Gene name | CST3 | |
| External IDs | ||
| Inhibitor classification | ||
| MEROPS | I25.004 | |
| Occurrence | ||
| Homology family | HBG244398 | |
| Parent taxon | Chordates | |
| Orthologue | ||
| human | mouse | |
| Entrez | 1471 | 13010 |
| Ensemble | ENSG00000101439 | ENSMUSG00000027447 |
| UniProt | P01034 | Q3U5K7 |
| Refseq (mRNA) | NM_000099 | NM_009976 |
| Refseq (protein) | NP_000090 | NP_034106 |
| Gene locus | Chr 20: 23.56 - 23.57 Mb | Chr 2: 148.56 - 148.57 Mb |
| PubMed search | 1471 |
13010
|
Cystatin C (also: CysC) is an endogenous protein that is used in kidney diagnostics to determine the glomerular filtration rate (GFR) .
The normal serum values in humans are between 0.53 and 0.95 mg / l for both sexes. Increased values are found with a reduced glomerular filtration rate (GFR) .
Cystatin C is a member of the cystatin family of cysteine proteases - inhibitors . Most nucleated cells produce cystatin C at a relatively constant rate; the production seems to remain the same even with inflammatory processes and other pathological conditions. Rare mutations in CST 3 - gene can hereditary amyloidosis and macular degeneration cause.
Cystatin C is filtered in the kidney, probably also secreted in tubular form, 99% reabsorbed in the proximal tubule and then broken down. Only the smallest amounts of unmetabolized cystatin C are excreted in the urine.
Clinical application
It is unclear to what extent factors other than the GFR influence the cystatin C plasma concentration. In people with chronic kidney disease, the elderly, children and patients with neuromuscular diseases, the plasma level tends to deviate from the GFR. There is also no mathematical formula available that estimates the GFR more precisely than the existing formulas for creatinine . Combinations of measuring and offsetting cystatin C and creatinine have achieved a higher sensitivity in kidney patients than the existing methods.