A 9-nt segment of a cellular mRNA can function as an internal ribosome entry site (IRES) and when present in linked multiple copies greatly enhances IRES activity.

ABSTRACT: This study addresses the properties of a newly identified internal ribosome entry site (IRES) contained within the mRNA of the homeodomain protein Gtx. Sequential deletions of the 5' untranslated region (UTR) from either end did not define distinct IRES boundaries; when five nonoverlapping UTR fragments were tested, four had IRES activity. These observations are consistent with other cellular IRES analyses suggesting that some cellular IRESes are composed of segments (IRES modules) that independently and combinatorially contribute to overall IRES activity. We characterize a 9-nt IRES module from the Gtx 5' UTR that is 100% complementary to the 18S rRNA at nucleotides 1132-1124. In previous work, we demonstrated that this mRNA segment could be crosslinked to its complement within intact 40S

SUBMITTER: Chappell SA 

PROVIDER: S-EPMC26470 | biostudies-literature | 2000 Feb

REPOSITORIES: biostudies-literature