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- Messenger RNP (messenger ribonucleoprotein) is mRNA with bound proteins. mRNA does not exist "naked" in vivo but is always bound by various proteins while being synthesized, spliced, exported, and translated in the cytoplasm. Messenger RNPs were first discovered in Alexander S. Spirin's laboratory in Moscow, Russia in 1964. The discovery was based in their study of fish embryo cytoplasm extracts, where they found these mRNPs. This finding was discovered after the mRNA of the fish embryo was centrifuged. The mRNA liquid separated into two parts, having the scientists question what is separate of the mRNA from the ribosomes. Spirin and his collaborators analyzed the mRNA against CsCl density gradients and discovered that parts of the mRNA were coated in proteins. The weight ratio of mRNPs was found to be 1:3, mRNA to protein. mRNPs were thus denoted as informosomes by the lab. There are three major informosomes found in mammalian cells: nuclear ribonucleoproteins, cytoplasmic informosomes, and polyribosomal messenger ribonucleoproteins. It was hypothesized by researchers that major roles of informosomes are to assist in mRNAs translocation from the nucleus to the cytoplasm, protect the mRNA against degradation, and help regulate protein formation. When mRNA is being synthesized by RNA polymerase, this nascent mRNA is already bound by RNA 5′ end 7-methyl-guanosine capping enzymes. Later, the pre-mRNA is bound by the spliceosome containing exon and intron definition complexes and proteins and RNA that catalyze the chemical reactions of splicing. Joan Steitz and Michael Lerner and collaborators showed that the small nuclear RNAs (snRNAs) are complexed into small nuclear Ribonuclear Proteins (snRNPs). Christine Guthrie and collaborators showed that specific snRNAs encoded by single copy genes in yeast base pair with the pre-mRNA and direct each step in splicing. The spliced mRNA is bound by another set of proteins which help in export from the nucleus to the cytoplasm. In vertebrates exon-exon junction are marked by exon junction complexes which in the cytosol can trigger nonsense mediated decay if the exon-exon junction is more than 50-55 nt downstream of the stop codon. (en)
- L'RNP messaggero (ribonucleoproteina messaggera) è l'mRNA legato a proteine. L'mRNA non esiste "nudo" in vivo ma è sempre legato da varie proteine mentre viene sintetizzato, maturato, esportato e tradotto nel citoplasma. (it)
- Матричные рибонуклеопротеины — комплекс мРНК и белков. В клетке мРНК почти никогда не существует в «голом виде», мРНК всегда связана со множеством различных белков, в процессе своего синтеза, сплайсинга, экспорта в цитоплазму и трансляции. В процессе синтеза мРНК РНК-полимеразой, новосинтезированная РНК сразу же связывается с кэпирующими ферментами. Потом происходит связывание с экзон и узнающими комплексами и сплайсинг при помощи . Прошедшая сплайсинг мРНК связывается с другим набором белков, которые помогают экспортировать её из ядра в цитоплазму. У позвоночных место соединения одного экзона с другим помечается специальными комплексами соединения экзонов, которые в цитозоле могут запускать , если место соединения одного экзона с другим расположено ниже стоп-кодона. (ru)
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- L'RNP messaggero (ribonucleoproteina messaggera) è l'mRNA legato a proteine. L'mRNA non esiste "nudo" in vivo ma è sempre legato da varie proteine mentre viene sintetizzato, maturato, esportato e tradotto nel citoplasma. (it)
- Messenger RNP (messenger ribonucleoprotein) is mRNA with bound proteins. mRNA does not exist "naked" in vivo but is always bound by various proteins while being synthesized, spliced, exported, and translated in the cytoplasm. (en)
- Матричные рибонуклеопротеины — комплекс мРНК и белков. В клетке мРНК почти никогда не существует в «голом виде», мРНК всегда связана со множеством различных белков, в процессе своего синтеза, сплайсинга, экспорта в цитоплазму и трансляции. (ru)
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- RNP messaggero (it)
- Messenger RNP (en)
- Матричные рибонуклеопротеины (ru)
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