synonymRibosomal protein(A general term for all proteins involved in the formation of ribosomes) Generally, it refers to ribosomal proteins
Ribosomal protein refers to the protein that constitutes the ribosome.
Since ribosomal proteins require a high concentration of salt solution and strong dissociation agent (such as CH3COOH or 3mol/L LiCl~4mol/L (NH2) 2CO with a high concentration of Mg2+) to separate them, such proteins are also called "eukaryotic proteins" relative to "ribosome related proteins".
Because in the process of ribosome self-assembly, such proteins bind to rRNA batch by batch to form large and small subunits of ribosome, these proteins can be divided into "primary binding proteins", "secondary binding proteins" and "late binding proteins" according to the order of binding to rRNA.
Escherichia coli ribosomal protein
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At present, the understanding of ribosomal proteins mainly comes from the understanding ofEscherichia coli（E. coli）Ribosome research.Most ribosomal proteins of Escherichia coli have been used in bi-directionalPolyacrylamide gel electrophoresisThe primary structure was determined and specific antibodies were developed.The above achievements andelectron microscopeIt is possible to further study the configuration of proteins in ribosomes.
ColiformRibosome small subunitThere are about 22 proteins (numbered S1 to S22) in theRibosome large subunitThere are about 34 proteins (numbered L1 to L36) in the.These proteins are immunologically independent, and only L7 and L12 show cross reaction with each other.All of these ribosomal proteins areBasic protein(The isoelectric point is about 10).In addition, except for the three groups listed below, the other ribosomal proteins are different from each other:
S20 and L26 have been proved to be the same protein, which is the only one that appears in both large and small subunits.
L7 and L12 are the N-terminal acetylated version and the internal methylated version of the same protein.
L8 is a composite of L7 (or L12) and L10.
In addition, two different forms of L31 have been found:relative molecular massA more complete version of 7.9 kD and a fragment of 7.0 kD.Except for S1 with a molecular weight of 61.2 kD, the molecular weights of the other ribosomal proteins are relatively concentrated between 4.4 kD and 29.7 kD.
Distribution of ribosomal small subunit proteins
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The distribution of various ribosomal proteins in ribosomes was mainly studied by recombination technology, chemical cross-linking technology, fluorescent labeling technology, immunoelectron microscopy and affinity chromatography.During the assembly of small ribosomal subunits (30S) of Escherichia coli, ribosomal proteins numbered S4, S7, S8, S15, S17 and S20 can bind directly to 16S rRNA;After the above first batch of proteins (collectively referred to as "primary binding proteins") and rRNA form a complex, the second batch of proteins (collectively referred to as "secondary binding proteins") numbered S5, S6, S9, S12, S13, S16, S18 and S19 combine with the previously formed complex;secondaryBinding proteinThe binding also makes the last batch of proteins (collectively referred to as "late binding proteins") numbered S2, S3, S10, S11, S14 and S21 more stable.
The binding of protein to the helix junction is critical to trigger correct RNA tertiary folding and to organize the overall structure of ribosomes.Almost all ribosomal protein structures contain spherical domains and extended domains that can connect RNA farther away from them.The additional stability of ribosomes comes from the neutralization of the basic functional groups in these ribosomal proteins to the mutually exclusive negative charges on the edge phosphate groups of the rRNA skeleton.The interactions between ribosomal proteins (such as electrostatic attraction and hydrogen bonding) also help to maintain the stability of the entire ribosomal structure.
