Substitution of just five nucleotides at and around the transcription start site of rat beta-actin promoter is sufficient to render the resulting transcript a subject for translational control.
Vertebrate mRNAs with a 5' terminal oligopyrimidine tract (5' TOP), including those encoding ribosomal proteins and elongation factors, are candidates for translational control in a growth-dependent fashion. The present study was designed to determine the minimal cis-regulatory element involved in this mode of regulation. We selected rat beta-actin mRNA, a typical translationally uncontrolled transcript, as a subject for gain-of-function analysis. Mutations at and around its cap site leading to the formation of a 7 pyrimidines long 5' TOP render the resulting transcript translationally repressed upon growth arrest of lymphosarcoma cells. In contrast, growth-dependent translational control of this mRNA in fibroblasts requires, in addition, a GC motif downstream of the 5' TOP. A similar motif is present in all ribosomal prtein mRNAs shown to be translationally controlled.
Biberman
Y
Y
Department of Biochemistry, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Meyuhas
O
O
D016475:3T3 Cells; D000199:Actins / Q000235:genetics*; D000818:Animals; D001482:Base Composition; D005786:Gene Expression Regulation; D019382:Human Growth Hormone / Q000235:genetics; D051379:Mice; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D051381:Rats; D013329:Structure-Activity Relationship
D000199:Actins; D019382:Human Growth Hormone