| CST6

Cystatin-6, also known as Cystatin-M, is a protein encoded by the CST6 gene. The cystatin superfamily comprises proteins containing multiple cystatin-like sequences. Some members are active cysteine protease inhibitors, while others have lost or may never have acquired this inhibitory activity. This superfamily includes three inhibitory families: type 1 cystatins (stefins), type 2 cystatins, and kininogens. Type 2 cystatin proteins are a class of cysteine protease inhibitors found in various human body fluids and secretions, where they appear to serve protective functions. The gene encodes a cystatin within the type 2 family, which is downregulated in metastatic breast tumor cells compared to primary tumor cells. The loss of its expression may be associated with the progression of primary tumors to a metastatic phenotype.
 

| Typical data

As the OD values of the standard curve may vary according to the conditions of the actual assay performance (e.g. operator, pipetting technique, wash technique or temperature effects), the operator should establish a standard curve for each test. Typical standard curve and data are provided below for reference only.

 

Concentration (ng/mL)	10	5	2.5	1.25	0.62	0.31	0.15	0
OD	2.22	1.56	0.92	0.63	0.42	0.25	0.18	0.08
Corrected OD	2.14	1.48	0.84	0.55	0.34	0.17	0.1	-

 

| Repeatability

Intra-assay Precision (Precision within an assay)：CV% < 10%; Inter-assay Precision (Precision between assays)：CV% < 10%
 

| Recovery

The recovery of Human CST6 spiked at three different levels in samples throughout the range of the assay was evaluated in various matrices.

 

Sample Type	Range(%)	Average Recovery(%)
Serum(n=8)	84-101	96
Plasma(n=8)	92-105	102
Cell Culture Supernates(n=8)	96-108	105

 

| Linearity

Samples were spiked with high concentrations of Human CST6 and diluted with Universal Diluent to produce samples with values within the range of the assay.

 

		Serum(n=4)	Plasma(n=4)	Cell Culture Supernates(n=4)
1 : 2	Range (%)	84-95	88-96	90-110
	Average (%)	91	93	96
1 : 4	Range (%)	89-103	87-108	105-115
	Average (%)	94	98	108