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A morpholino, also known as a morpholino oligomer and as a phosphorodiamidate morpholino oligomer (PMO), is type of oligomer molecule (colloquially, an oligo) used in molecular biology to modify gene expression. The molecular structure has a backbone of methylenemorpholine rings and phosphorodiamidate linkages. Morpholinos block access of other molecules to small (~25 base) specific sequences of the base-pairing surfaces of ribonucleic acid (RNA). Morpholinos are used as research tools for reverse genetics by knocking down gene function. They are being studied for application in medicine. This article discusses only the morpholino antisense oligomers, which are nucleic acid analogs. The word "morpholino" can occur in other chemical names, referring to chemicals containing a six-membered morpholine ring. To help avoid confusion with other morpholine-containing molecules, when describing oligos "Morpholino" is often capitalized as a trade name, but this usage is not consistent throughout the scientific literature. Gene knockdown is achieved by preventing cells from making a targeted protein. Morpholinos can also modify the splicing of pre-mRNA. Knocking down gene expression is a powerful method for learning about the function of a particular protein; in similar manner, causing a specific exon to be spliced out of a protein can help to determine the function of the protein moiety encoded by that exon or can sometimes knock down the protein activity altogether. These molecules have been applied to studies in several model organisms, including mice, zebrafish, frogs, and sea urchins. Morpholinos are in development as pharmaceutical therapeutics targeted against pathogenic organisms such as bacteria or viruses and for amelioration of genetic diseases. These synthetic oligos were conceived by James E. Summerton (Gene Tools) and developed in collaboration with Dwight D. Weller (formerly Antivirals, renamed AVI BioPharma, renamed Sarepta Therapeutics). ==Structure== Morpholinos are synthetic molecules that are the product of a redesign of natural nucleic acid structure. Usually 25 bases in length, they bind to complementary sequences of RNA by standard nucleic acid base-pairing. In terms of structure, the difference between Morpholinos and DNA is that, while Morpholinos have standard nucleic acid bases, those bases are bound to morpholine rings instead of deoxyribose rings and linked through phosphorodiamidate groups instead of phosphates.〔 This may be easiest to visualize by referring to the first figure and comparing the structures of the two strands depicted there, one of RNA and the other of a Morpholino. Replacement of anionic phosphates with the uncharged phosphorodiamidate groups eliminates ionization in the usual physiological pH range, so Morpholinos in organisms or cells are uncharged molecules. The entire backbone of a Morpholino is made from these modified subunits. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Morpholino」の詳細全文を読む スポンサード リンク
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