DESCRIPTION

CD98 is a 125-kDa type II membrane glycoprotein heterodimer composed of a 40-kDa non-glycosylated light chain (amino-acid transporter) and an 85-kDa glycosylated heavy chain (CD98hc). CD98hc also interacts with certain integrin b-subunits to regulate cell migration, survival, proliferation, and adhesion/polarity. CD98hc is overexpressed on the cell surface of many cancers and increased CD98hc expression is associated with the development and progression of tumors. Molecular orientation studies have demonstrated that the C-terminal tail of human CD98 (hCD98), which contains a PDZ-binding domain, is extracellular.

PRINCIPLE OF THE ASSAY

Sandwich ELISA structure (Detection antibody labeled with HRP) A capture antibody is pre-coated onto the bottom of wells which binds to analyte of interest. A detection antibody labeled with HRP also binds to the analyte. TMB acts as the HRP substrate and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns solution yellow. The color intensity is proportional to the quantity of bound protein which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 8 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 16 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	8	11.18	0.47	4.17
2	8	2.50	0.16	6.27
3	8	0.69	0.04	6.11

Inter-assay Precision

Sample	n	Mean (ng/mL)	SD	CV%
1	16	10.51	1.06	10.05
2	16	2.67	0.22	8.36
3	16	0.73	0.06	8.26

RECOVERY

The recovery of human CD98/SLC3A2 spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Human serum	1:128	96	94-99
	1:256	93	84-99
Cell lysate	1:512	98	96-99
	1:1,024	88	78-94

LINEARITY

To assess the linearity of the assay, samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. (The human serum was initially diluted 1:16. The cell lysate was initially diluted 1:64.)

		Human serum	Cell lysate
1:2	Average% of Expected	100	100
	Range (%)	-	-
1:4	Average% of Expected	90	109
	Range (%)	89-91	106-111
1:8	Average% of Expected	84	111
	Range (%)	77-90	106-115
1:16	Average% of Expected	79	111
	Range (%)	74-84	106-116

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human Human CD98/SLC3A2 Sandwich ELISA Kit produced at Sunlong Medical™.