|Detection of Human, Mouse, and Rat eIF5A by Western Blot. Western blot shows lysates of 786‑O human renal cell adenocarcinoma cell line, C2C12 mouse myoblast cell line, and NR8383 rat alveolar macrophage cell line. PVDF membrane was probed with 1 µg/mL of Sheep Anti-Human/Mouse/Rat eIF5A Antigen Affinity-purified Polyclonal Antibody (Catalog # AF7558) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for eIF5A at approximately 18 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
eIF5A (Elongation initiation factor 5A; also eIF5A1, Rev-binding factor and eIF-4D) is a 16-19 kDa member of the eIF5A family of molecules. It is ubiquitously expressed, being found in all human cells examined. eIF5A acts as a stabilizer of RNA transcripts and acts as a positive modulator of p53-mediated apoptosis. It also may be involved in the formation of the first peptide bond during select protein synthesis, and is known to be essential for cell cycle progression through G1/S. The human eIF5A precursor is 154 amino acids (aa) in length. It contains a 71 aa DOHH (deoxyhypusine hydroxylase)-binding site (aa 20-90) and a 69 aa RNA-binding domain (aa 84-152). eIF5A undergoes a posttranslational modification that converts the precursor peptide into a mature molecule. This modification occurs on Lys50, and involves the transfer and hydroxylation of an aminobutyl sequence from spermidine, creating a unique amino acid termed hypusine (hydroxyputrisine lysine). When hypusine is unacetylated, eIF5A is active; when acetylated, eIF5A is inactive. Nonhypusinated eIF5A is found in both cytoplasm and nucleus, while hypusinated eIF5A is targeted to the cytoplasm. There is one isoform variant that shows a 32 aa substitution for aa 1-32. Over aa 85-154, human and mouse are identical in aa sequence. Over the same aa sequence, human eIF5A (on Chr 17p13) also shares 98% and 69% aa identity with human eIF5A1-Like (on Chr 10q22) and human eiF5A2 (on Chr 3q26), respectively.