Recombinant Human VEGF-Ax Protein

Recombinant Human VEGF-Ax Protein Summary

Product Specifications

Product Datasheets

Carrier Free

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.

Background: VEGF

Vascular endothelial growth factor (VEGF or VEGF-A), also known as vascular permeability factor (VPF), is a potent mediator of both angiogenesis and vasculogenesis in the fetus and adult (1, 2). It is a member of the PDGF family that is characterized by the presence of eight conserved cysteine residues and a cystine knot structure (3). Humans express two sets of alternatively spliced isoforms of 121, 145, 165, 183, 189, and 206 amino acids (aa) in length (3, 4). Isoforms other than VEGF₁₂₁ contain basic heparin-binding regions and are not freely diffusible (3, 4). VEGF₁₆₅ appears to be the most abundant and potent of the angiogenic isoform set, followed by VEGF₁₂₁ and VEGF₁₈₉ (3, 5). The anti-angiogenic or “b” set of isoforms is differentially spliced to contain six alternative amino acids at the C-terminus, and are the more highly expressed isoforms in normal adult tissue (6). VEGF_165b, like VEGF₁₂₁ but unlike most angiogenic isoforms, does not bind heparins and is therefore diffusible (3). Human VEGF₁₆₅ shares 88% aa sequence identity with corresponding regions of mouse and rat, 96% with porcine, 95% with canine, and 93% with feline, equine and bovine VEGF₁₆₅, respectively. In addition to alternatively spliced VEGF isoforms, multiple fragments of VEGF can be generated by extracellular proteolysis (4). VEGFs bind the type I transmembrane receptor tyrosine kinases VEGF R1 (also called Flt-1) and VEGF R2 (Flk-1/KDR) on endothelial cells (3). Although VEGF affinity is highest for binding to VEGF R1, VEGF R2 appears to be the primary mediator of VEGF angiogenic activity (3, 5). VEGF₁₆₅ binds the semaphorin receptor, Neuropilin-1 and promotes complex formation with VEGF R2 (7). An extended form of VEGF-A, known as VEGF-Ax, results from the C-terminal addition of 22 amino acids (8). VEGF-Ax is produced by vascular endothelial cells, retains the ability to bind VEGF R2 but not Neuropilin-1, and functions as an anti-angiogenic protein (8). VEGF is required during embryogenesis to regulate the proliferation, migration, and survival of endothelial cells (3, 5). In adults, VEGF functions mainly in wound healing and the female reproductive cycle (5). Pathologically, it is involved in tumor development and tumor vascular leakage (9). Circulating VEGF levels correlate with disease activity in autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, and systemic lupus erythematosus (10). VEGF is induced by hypoxia and cytokines such as IL-1, IL-6, IL-8, Oncostatin M, and TNF-alpha (5, 11).

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