Description : |
Human IGF binding protein 4 (IGFBP-4) was isolated from human plasma based on its ability to bind immobilized IGF-I. Human IGFBP-4 cDNA encodes a 258 amino acid (aa) residue precursor protein with a predicted 21 aa residue signal peptide that is pr centigradeessed to generate the 237 aa residue mature human IGFBP-4. The human IGFBP-4 contains a potential N-linked glycosylation site and shares approximately 90% amino acid sequence identity with both the mouse and rat IGFBP-4. According to the nomenclature of IGFBPs defined at the 4th International Symposium of IGFs (1997, Tokyo), six high-affinity IGF binding proteins (IGFBP-1, -2, -3, -4, -5, -6), and four IGFBP-related proteins (IGFBPr-1, - 2, -3, -4) have now been identified. All IGFBPs have a high cysteine content and share conserved cysteine residues that are clustered in the amino- and carboxy-terminal thirds of the molecule. |
Source : |
Mammalian cells |
Species : |
Human |
Form : |
Lyophilized from a 0.2 μm filtered solution in PBS, pH 7.4. |
Bio-activity : |
Measured by its ability to inhibit the biological activity of rhIGF-I or rhIGF-II on MCF-7 cells (Karey, K.P. et al., 1988, Cancer Research 48:4083). The ED50 for this effect is typically 0.03 - 0.09 μg/mL in the presence of 14 ng/mL rhIGF-II. |
Molecular Mass : |
Met 17 from the CD33 signal peptide was retained in the recombinant mature human IGFBP-4. The 238 amino acid residue recombinant mature human IGFBP-4 has a calculated molecular mass of approximately 26 kDa. As a result of glycosylation, the recombinant protein migrates as a 32 kDa and 25 kDa protein under reducing and non-reducing conditions, respectively. |
Endotoxin : |
< 1.0 eu per 1 μg of the cytokine as determined by the lal |
Purity : |
>97%, as determined by SDS-PAGE and visualized by silver stain. |
Usage : |
FOR RESEARCH USE ONLY |
Quality Control Test : |
Lyophilized samples are stable for up to six months at -20 centigrade to -70 centigrade. Upon reconstitution, this cytokine, in the presence of a carrier protein, can be stored under sterile conditions at 2 - 8 centigrade for one month or at -20 centigrade to -70 centigrade in a manual defrost freezer for three months without detectable loss of activity. |
Reconstitution : |
It is recommended that sterile PBS containing at least 0.1% human serum albumin or bovine serum albumin be added to the vial to prepare a st centigradek solution of no less than 25 μg/mL. |
Warning : |
Avoid repeated freeze-thaw cycles. |