Humanin

n/an/an/an/an/an/an/an/an/an/aHumanin is a micropeptide encoded in the mitochondrial genome by the 16S ribosomal RNA gene, MT-RNR2. Its structure contains a three-turn α-helix, and no symmetry. Humanin is a micropeptide encoded in the mitochondrial genome by the 16S ribosomal RNA gene, MT-RNR2. Its structure contains a three-turn α-helix, and no symmetry. In in vitro and animal models, it appears to have cytoprotective effects. Humanin is encoded in the mitochondrial genome by the 16S ribosomal RNA gene, MT-RNR2. Multiple isoforms are found in the nuclear genome and are named MTRNR2L followed by a number. The expressed peptide contains a three-turn α-helix, and has no symmetry. The length of the peptide depends on where it is produced. If it is produced inside the mitochondria it will be 21 amino acids long. If it is produced outside the mitochondria, in the cytosol, it will be 24 amino acids long. Both peptides have been shown to have biological activity. The rat, Rattus norvegicus, has a gene, rattin, that encodes a 38 amino acid peptide homologous to humanin. The two genes produce cDNAs that show 88% sequence identity. The peptides are 81% identical, with the carboxyl terminal sequence 14 amino acids longer in rattin. Of the 24 amino acids in the rest of the sequence, 20 are the identical. Humanin has several cytoprotective effects. Extracellular interaction with a tripartite receptor composed of gp130, WSX1, and CNTFR, as well as interaction with the formyl peptide receptor 2 (formylpeptide-like-1 receptor) have been published. Intracellular interaction with BAX, tBID, IGFBP3, and TRIM11 may also be required for the effects of humanin.