Photochemical cross-linking of translation initiation factor 3 to Escherichia coli 50S ribosomal subunits

Translation initiation factor 3 (IF-3) was bound noncovalently to Escherichia coli 50S ribosomal subunits. Irradiation of such complexes with near-ultraviolet light (greater than 285 nm) resulted in covalent attachment of initiation factor 3 to the 50S subunit. Photo-cross-linking attained its maxim...

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Bibliographic Details
Published in:Biochemistry (Easton) 1983-03, Vol.22 (6), p.1483-1489
Main Authors: Schwartz, I, Vincent, M, Strycharz, W A, Kahan, L
Format: Article
Language:English
Subjects:
Bacterial Proteins - radiation effects
Escherichia coli
Escherichia coli - metabolism
Immunochemistry
Peptide Initiation Factors - radiation effects
Photochemistry
Prokaryotic Initiation Factor-3
Protein Binding - radiation effects
Ribosomal Proteins - radiation effects
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Summary:Translation initiation factor 3 (IF-3) was bound noncovalently to Escherichia coli 50S ribosomal subunits. Irradiation of such complexes with near-ultraviolet light (greater than 285 nm) resulted in covalent attachment of initiation factor 3 to the 50S subunit. Photo-cross-linking attained its maximum level of 40% of that which was noncovalently bound after 90 min of irradiation. Cross-linking was abolished in the presence of either 0.5 M NH4C1 or 0.25 mM aurintricarboxylic acid, indicating that specific binding of initiation factor 3 to the ribosome was a prerequisite for subsequent covalent attachment. Further analysis showed that all the IF-3 was covalently bound to a small number of 50S subunit proteins. The major cross-linked proteins were identified as L2, L7/L12, L11, and L27 by immunochemical techniques. These results are discussed in light of the proposed mechanism for IF-3 function.
ISSN:0006-2960
DOI:10.1021/bi00275a024