Cystatin C

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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
Gene name CST3
External IDs
Inhibitor classification
MEROPS I25.004
Homology family HBG244398
Parent taxon Chordates
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.

Web links

Individual evidence

  1. ^ A b Lesley A. Stevens, Shani Shastri, Andrew S. Levery: Assessment of Renal Function. In: Jürgen Floege, Richard J Johnson, John Feehally: Comprehensive Clinical Nephrology. 4th edition, St. Louis 2010, p. 36 f.