| Lens epithelium-derived growth factor (LEDGF, also PC4 and SFRS1-interacting protein, PSIP, transcriptional co-activator p75/p52, and dense fine speckles 70kD protein) is a ubiquitously expressed, 75kD member of the hepatoma-derived growth factor (HDGF) family of proteins. Human LEDGF is 530aa in length. LEDGF contains a PWWP domain (aa 1-64), a nuclear localization signal (aa146-156), two coiled-coil regions (aa306-334 and 371-395), and four helical regions (aa347-362, 370-381, 394-403 and 410-425). In addition, there are multiple serine and threonine residues that are sites of potential phosphorylation. The protein is highly charged, with lysine, arginine, glutamate, and aspartate comprising 39% of the total residues. Two splicing variants produce a second isoform known as p52. p52 has an 8aa substitution corresponding to aa326-333 of LEDGF, and a deletion of the final 197aa found in LEDGF. Human LEDGF shares 92% aa sequence identity with mouse and rat LEDGF. LEDGF functions as a transcriptional co-activator that is involved in neuroepithelial stem cell differentiation and neurogenesis. It is also a survival factor that is inducible by oxidative stress and protects cells from various stresses by upregulating stress- responsive genes. For example, TNF-alpha elevates the expression of LEDGF, which increases the expression of endogenous gamma-GHS-HS, the catalytic subunit of the regulating enzyme in GSH biosynthesis that constitutes a protective mechanism in limiting oxidative stress induced by inflammatory cytokines. LEDGF is also a major autoantigen in atopic dermatitis and other inflammatory conditions involving dysregulated apoptosis. Anti-LEDGF autoantibodies have been shown to have cytotoxic activity, suggesting their involvement in pathogenesis. In apoptotic cells, caspases cleave this protein at three sites within functionally important domains, generating two fragments of 65 and 58kD. Caspase cleavage abolishes the survival function of LEDGF and may generate variants of the protein that enhance apoptosis. LEDGF has also been shown to interact with lentiviral integrase (IN) proteins, including HIV-1 IN, directly, determining their nuclear localization and their tight association with nuclear DNA. This prevents proteosomal degradation of these proteins. Recombinant protein corresponding to Met1-Gln333 of human LEDGF, expressed in E. coli. Uniprot/Accession: NP_066967 SDS-PAGE: 52kD, reducing conditions Activity: Measured by its ability to enhance neurite outgrowth of E16-E18 rat embryonic cortical neurons. Able to significantly enhance neurite outgrowth when immobilized at 1.5-15ug/ml on a nitrocellulose-coated microplate. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile PBS. 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. |
