Dictionary:

nucleoprotein

  (nū'klē-ō-prō'tēn', -prō'tē-ĭn, nyū'-)

Any of a group of complexes composed of protein and nucleic acid and found in the nuclei and cytoplasm of all living cells, as in chromatin and ribosomes, and in viruses.

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.

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 acid 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.

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 infection.

The complex of proteins and nucleic acids found in the cell nucleus.

Any one of a special group of protein substances in combination with nucleic acid. The essential component is the phosphoric acid radical. The nucleoproteins are generally confined to the nucleus of the cell and are intimately associated with chromosome and gene function.

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Any of a class of conjugated proteins, consisting of nucleic acids and simple proteins, e.g. a histone.

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