Technical Data
Insulin Binding Protein 4, Recombinant, Human, Western Blot Positive Control (Insulin-like Growth Factor-binding Protein 4, IBP-4, IGF-binding Protein 4, IGFBP-4, IBP4)
Molecular Biology Storage: -20CShipping: Blue Ice
The insulin like growth factors (IGFs) are the major growth- promoting factors in the plasma. IGFs are secreted by a variety of cells and exert a multitude of effects on cellular survival, growth and differentiation. The A and B domains of IGFs are identical to insulin. IGF initiates their biological action through binding to the type IGF receptor (IGF-1R), a heterotrimeric protein complex with a tyrosine kinase activity. The IGF-IIR lacks the kinase activity and is actually identical to the mannose- 6-phophate receptor. Unlike most other peptide hormones, IGFs are complexed with specific binding proteins in the plasma known IGF Binding proteins (IGFBPs). At least 6 related IGFBPs (IGFBP1-6) have been well characterized. Recently, IGFBP-7/Mac25/prostacyclin- stimulating factor (PSF)/tumor adhesion factor (TAF) was originally identified as a cDNA derived from leptomeninges. These proteins are present in plasma in high concentration as compared to the membrane IGFRs. Therefore, IGFBPs have the potential to modulate the IGF action. IGFBPs have been shown to either inhibit or stimulate the IGF effects. The primary structures of mammalian IGFBPs appear to contain three distinct domains of roughly equivalent sizes: the conserved N-terminal domain, the highly variable mid region, and the conserved C-terminal domain. Human IGFBPs share approximately 36% identity.

Insulin-like growth factor binding protein-4 (IGFBP-4, 22-237aa mature protein, protein accession # P22692) is expressed in multiple tissues including adrenal, testis, spleen, heart, lung, kidney, liver, stomach, hypothalamus, and brain cortex. High expression levels are found in the non-paranchymal cells of the liver.4 IGFBP-4 is the predominant IGFBP expressed by human osteoblast-like cells and is also expressed in skin fibroblasts.

Recombinant human IGFBP4 (mature protein 22-258aa) was expressed in NSO cells with a CD33 signal peptide.

Molecular Weight:

Suitable for use in Western Blot. Not suitable for use in ELISA. Other applications not tested.

Recommended Dilution:
Western Blot: 10ul/lane. SDS may crystallize in cold conditions. It should redissolve by warming before taking it from the stock. It should be heated once prior to loading on gels. If the product has been stored for several weeks, then it may be preferable to add 5ul of fresh 2x sample buffer per 10ul of the Western Blot solution prior to heating and loading on gels.
Optimal dilutions to be determined by the researcher.

Storage and Stability:
Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile buffer or ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

Molecular Weight:
Source: NSO cells
Purity: Highly Purified (~95%)
Concentration: Not determined.
Form: Supplied as a lyophilized powder from PBS, 0.05% sodium azide.

Important Note: This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.
1. Latour D (1990) Mol. Endocrinol. 4, 1806. 2. Shimasaki S (1990) Mol Endocrinol. 4, 1451. 3. Kiefer MC (1991) JBC 266, 9043.

Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.