Messenger ribonucleoprotein particles

Singh, O.P., Bjorkroth, B., Masich, S., Wieslander, L. and Daneholt, B. (1999) The intranuclear movement of Balbiani ring pre-messenger ribonucleoprotein particle. Exp. Cell Res., 251, 135-146. 

Elkaim R, Thomassin H, Niedergang C, Egly JM, Kempf J, Mandel P (1983) Adenosine diphosphate ribosyltransferase and protein acceptors associated with cytoplasmic free messenger ribonucleoprotein particles. Biochimie 65 653-659... 

Recently, we have demonstrated the existence of a poly(ADPR) polymerase activity associated with cytoplasmic free messenger ribonucleoprotein particles (mRNP) isolated from mouse plasmacytoma cells [4]. The enzyme does not require DNA for activity and is able to produce an ADP-ribosylation of some of the mRNP proteins. We have extended our observations to Krebs II ascites-tumor cells and to rat liver. In the present report, we will discuss some properties of this enzyme, particularly the activation by RNase A. 

Egly JM, Schmitt M, Elkaim R, Kempf J (1981) Protein kinases and their protein substrates in free messenger ribonucleoprotein particles and polysomes from mouse plasmacytoma cells. Eur J Biochem 118 379-387... 

Poly(ADP-ribosyl)ation is generally described as a nuclear event. However, extranuclear poly(ADP-ribose) polymerase activities have been detected in the cytosol of baby hamster kidney ceUs (1), the ribosomal fraction of HeLa cells (2) and rat testis (3). The activities looked like the nuclear enzyme in diat they totally or partially depended on DNA. We have previously reported the association of a poly(ADP-ribose) polymerase with a specific ribonucleoprotein complex, namely free messenger ribonucleoprotein particles (free mRNP) (4-6). The enzyme has the particularity to be DNA-independent. In diis paper, we have b n interested in the proteins which are poly(ADP-ribosyl)ated in free mRNP. We also present evidence of the existence of a poly(ADP-ribose) glycohydrolase in free mRNP. 

Hershey, J. W. B., 1982, Messenger ribonucleoprotein particles, in Protein Biosynthesis in Eukaryotes (R. Perez-Bercoff, ed.), pp. 157-166, Plenum Publishing, New York. 

Spohr, G., Granboulan, N., Morel, C., and Scherrer, K., 1970, Messenger RNA in HeLa cells An investigation of free and polyribosome-bound cytoplasmic messenger ribonucleoprotein particles by kinetic labelling and electron microscopy, Eur. J. Biochem. 17 296. 

Jones, C., and Ehrenfeld, E., 1983, The effect of poliovirus infection on the translation in vitro of VSV messenger ribonucleoprotein particles. Virology 129 415. 

Henshaw, E. C. 1968. Messenger RNA in rat liver polyribosomes evidence that it exists as ribonucleoprotein particles. J. Molec. Biol., 36 401-413. 

Nonribosomal RNA appears in the cytoplasm in the form of ribonu-cleoprotein particles called informosomes (Spirin et ah, 1964 Spirin, 1969). Such ribonucleoprotein particles, which are mostly not bound to ribosomal subunits, have been found in a variety of tissues. They are in part incorporated into polyribosomes (see Lebleu et ah, 1971 Knochel and Tiedemann, 1972 Bonanou-Tzedaki et ah, 1972). The appearance of messenger-ribonucleoprotein complexes in the polysomes is a slow process as compared to the synthesis of nuclear RNA. In chick embryos newly synthesized messenger (nonribosomal) RNA is detectable in polyribosomes after about 30 minutes. The time sequence of incorporation of mRNA into polyribosomes does not change when the RNA synthesis is completely blocked after 15 minutes by actinomycin D (Knochel, 1972b). In HeLa cells mRNA appears in the polysomes after a 15-20 minutes lag phase (Penman et ah, 1968). 

A ribosome- and polysome-associated poly(ADPR) polymerase activity was reported by Roberts et al. [29] and Burzio et al. [30]. We have demonstrated that ADP-ribosyl transferase activity is associated with free ribonucleoprotein particles carrying messenger RNA, the so-called free mRNP particles [31]. 

ADP-Ribosyl Transferase of Mitochondria and of Cytoplasmic Ribonucleoprotein Particles Containing Silent Messenger RNA... 

Poly(ADP-ribose) polymerase transferase was initially investigated in the nuclei of eucaryotic cells (1-4). Considering the developing but still limited understanding regarding the presence and the function of ADP-ribosylation reactions in extra nuclear compartments (5-7), we became interested in ADP-ribosylation of two sub-cellular entities mitochondria, and free ribonucleoprotein particles mRNP particles the latter carry silent messenger RNAs (mRNAs). 

Karlson s model is a direct extrapolation of the model of bacterial induction and repression proposed by Jacob and Monod However, the characteristics of RNA and protein synthesis are different in nucleated plant and animal cells, and in bacteria (1) ribosomal RNA is a major product of gene transcription in nucleated cells (2) a large part of the DNA like RNA, i.e. presumably messenger RNA, which is synthesized in the nucleus is also degraded there. This suggests a selective restriction of some RNA in the nucleus (3) cytoplasmic messenger RNA may be predominantly transferred from the nucleus as a complex, with a ribonucleoprotein ribosomal particle, and then directly assembled into polysomes. The rate of formation or maturation of ribosomes may directly influence the rate of transfer of messenger to the cytoplasm. 

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