Ribosomal Proteins

Ribosomal Proteins

Ribosomal Proteins - As mentioned previously, the E. coli ribosome contains 53 proteins, 21 in the 30S subunit and 34 in the 50S subunit. 820 and L26, formerly thought to be two proteins are identical.

Proteins L 7 and LI2 differ only in the presence of an N-termiI1al group in the, former.

L8, once thought to be unique, has been shown to be an aggregate of L7, L12 and L10. All E. coli ribosome proteins have distinct nonhomologous amino acid sequences,

with the exception of the two pairs mentioned above (820- L26 and L7- LIZ), which occur in 3-4 copies.

A study by Hardy (1975) indicates that ribosomes in vivo have one copy of each ribosomal protein, except for L7-L12 which occurs in 3-4 copies.

There appears to be one copy per 70S ribosomes of that identical proteins S20-L26. Immune electron microscopy studies show that several proteins, e.g.

S4, S7 and L6, have multiple antibody-binding sites situated at different points on the subunit surface.

This indicates that the proteins have a highly extended conformation two proteins, 815 and S18,

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