Identification of the proteins interacting with tRNA in rat liver small ribosomal subunits

Abstract

Irradiation at 254 nm of the rat liver 40 S ribosomal subunit—poly(U)—Phe[32P]tRNA complex induced a covalent linkage of tRNA with a limited number of ribosomal proteins. After RNA hydrolysis, S10 was found to be the protein most highly labeled by radioactive nucleotides. Some radioactivity was also associated with protein S6‐6a, S3a, S2 and S13–15.

tRNA binding modifies the properties of the small ribosomal subunit of rat liver

“…The existence of such a complex could alreadly be predicted from previous observations that tRNA protects the small subunits against heat inactivation even in the absence of mRNA (1). We have recently shown that irradiation at 254 nm of a mixture of PheI32PItRNA and 40S subunits in the presence of poly(U) results in the covalent labeling of a limited amount of ribosomal proteins (14). We therefore decided to check if 114CIPhe-tRNA could be crosslinked with 40S subunits not only in the presence, but also in absence of poly(U), which would further support the existence of a weak interaction between tRNA and 40S subunits.…”

“…When treated with 1.25M LiCl, these monomers retained all their protein content and activity while dimers were partially deproteinized into inactive core-particles. We have recently reported that tRNA bound to 40S subunits in the presence of mRNA photoreacts with a limited number of 40S subunit proteins (14). These proteins should interact directly with tRNA and it is quite possible that other proteins also interact but cannot be crosslihked with it.…”