Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.


A generic term for any member of a large class of proteins associated with nucleic acid molecules. Nucleoprotein complexes occur in all living cells and in viruses, where they play vital roles in reproduction and protein synthesis.

Classification of the nucleoproteins depends primarily upon the type of nucleic acid involved—deoxyribonucleic acid (DNA) or ribonucleic acid (RNA)—and on the biological function of the complex. Deoxyribonucleoproteins (complexes of DNA and proteins) constitute the genetic material of all organisms and of many viruses. They function as the chemical basis of heredity and are the primary means of its expression and control. Most of the mass of chromosomes is made up of DNA and proteins whose structural and enzymatic activities are required for the proper assembly and expression of the genetic information encoded in the molecular structure of the nucleic acid. See Deoxyribonucleic acid (DNA)

Ribonucleoproteins (complexes of RNA and proteins) occur in all cells as part of the machinery for protein synthesis. This complex operation requires the participation of messenger RNAs (mRNAs), amino acyl transfer RNAs (tRNAs), and ribosomal RNAs (rRNAs), each of which interacts with specific proteins to form functional complexes called polysomes, on which the synthesis of new proteins occurs. See Ribonucleic acid (RNA)

In simpler life forms, such as viruses which infect animal and plant cells and bacteriophages which infect bacteria, most of the mass of the viral particle is due to its nucleoprotein content. The material responsible for the hereditary continuity of the virus may be DNA or RNA, depending on the type of virus, and it is usually enveloped by one or more proteins which protect the nucleic acid and facilitate infections. See Bacteriophage, Chromosome, Nucleic acid, Virus

A typical human diploid nucleus contains 5.6 × 10-12 g of DNA. This DNA is arranged in 23 pairs of chromosomes differing in size and DNA content. The large number 1 chromosome, for example, contains 0.235 × 10-12 g of DNA, while the much smaller chromosome number 22 contains only 0.046 × 10-12 g. The DNA double-helix of chromosome 1 is actually 7.3 cm long, but this thin filamentous molecule is packaged to form a chromosome less than 10 micrometers long. The enormity of the packing problem can be appreciated from the fact that the average human contains about 100 g of DNA, and 0.5 g would reach from the Earth to the Sun! The reduction in size is largely due to interactions between the DNA and sets of small basic proteins called histones. All somatic cells of higher organisms contain five major histone classes, all of which are characterized by a high content of basic (positively charged) amino acids.

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a complex consisting of a nucleic acid and a protein. Nucleoproteins are widespread in nature. Deoxyribonucleoproteins and ribonucleoproteins are distinguished according to the nucleic-acid component. Deoxyribonucleoproteins constitute the chromatin matter in the nucleus of all cells and are present in the bodies of spermatozoa. Basic proteins called histones are the main protein component of deoxyribonucleoproteins. Smaller basic proteins called protamines occur in the spermatozooa of some animals, mainly birds and fish. Histones and protamines at neutral pH carry a large positive charge, which ensures a strong electrostatic interaction with nucleic acids, which are negatively charged. Deoxyribonucleoproteins are believed to be distributed in the grooves of the double helix of deoxyribonucleic acid, where they stabilize the helical structure and regulate the matrix activity of DNA. Many viruses, informosomes, and ribosomes consist of ribonucleoproteins (seeINFORMOSOMES).


Finean, J. Biologicheskie ul’trastructury. Moscow, 1970. (Translated from English.)
Khimiia biologicheski aktivnykh prirodnykh soedinenii. Moscow, 1970.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


Any member of a class of conjugated proteins in which molecules of nucleic acid are closely associated with molecules of protein.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
LIPS, luciferase immunoprecipitation system; NA, not applicable (ELISA was performed only for samples with positive results in other assays); NP, nucleoprotein; VP40, matrix protein.
Like the flu virus's evolving nucleoprotein, the ancestral receptor's structure had to be buttressed before it could withstand the mutations that would make the receptor choosier.
Baculoviral clone selection and expression recombinant entire (N-PPRV) and truncated nucleoprotein of PPRV (420-525N-PPRV): Recombinant baculoviruses expressing NPPRV and 420-525 NPPRV were kindly gifted by Dr.
Derivation of the nucleoproteins (NP) of influenza A viruses isolated from marine mammals.
[3] Nonstandard abbreviations: PB2, polymerase basic protein 2; PA, polymerase acidic protein; HA, hemagglutinin; NP, nucleoprotein; NA, neuraminidase; M, matrix; NS, nonstructure; RT, reverse transcription; Tm, melting temperature; TR, triple reassortant; EA, Eurasian avianlike.
The absence of fast green staining in sperm after DNA extraction by TCA and their retention of a high concentration of arginine reaction products suggests that a conversion from a primarily histone type of basic nucleoprotein to a more arginine-rich, protamine-like protein accompanies spermiogenesis in these spiders.
However, eukaryotic cells contain an additional level of information superimposed on the DNA double helix in the form of a complex nucleoprotein entity generically termed "chromatin." Recent studies have highlighted the instructive nature of this "DNA packaging" in regulating the interactions of the enzymatic machines of replication, transcription, recombination, and repair with DNA.
Eventually, viruses generally were found to contain either RNA or DNA, which means they are nucleoprotein rather than merely protein.
There is in fact previous evidence that nucleoprotein complexes released into the extracellular milieu can elicit definite cellular responses.
We generated nucleotide alignments for each of the 8 segments of the virus genome (HA, matrix protein [MP], NA, nucleoprotein [NP], nonstructural [NS], polymerase acidic [PA], polymerase basic 1 [PB1], and polymerase basic 2 [PB2]) by using MUSCLE version 3.8.31 (16).
The conserved viral proteins of influenza virus, such as nucleoprotein (NP) and matrix 1 protein (M1), are the main targets recognized by host virus-specific CD8+ cytotoxic lymphocytes [10, 11].