Translation Initiation from Conserved Non-AUG Codons Provides Additional Layers of Regulation and Coding Capacity.

and are homologs specifying transcription activators that drive the transcriptional response to amino acid limitation. The mRNA contains two upstream open reading frames (uORFs) in its >700-nucleotide (nt) 5' leader, and its expression is controlled at the level of translation in response to amino acid starvation. We used cell extracts and obtained data indicating that uORF1 and uORF2 are functionally analogous to uORF1 and uORF4, respectively, in controlling translation.

Circadian clock regulation of mRNA translation through eukaryotic elongation factor eEF-2.

The circadian clock has a profound effect on gene regulation, controlling rhythmic transcript accumulation for up to half of expressed genes in eukaryotes. Evidence also exists for clock control of mRNA translation, but the extent and mechanisms for this regulation are not known. In Neurospora crassa, the circadian clock generates daily rhythms in the activation of conserved mitogen-activated protein kinase (MAPK) pathways when cells are grown in constant conditions, including rhythmic activation of the well-characterized p38 osmosensing (OS) MAPK pathway.

Anti-Sm autoantibodies in MRL mice: analysis of precursor frequency.

Individual MRL-lpr mice vary in their capacity to generate anti-Sm autoantibodies spontaneously. We have compared the frequency of B-cell precursors for this autoantibody in serologically negative and serologically positive MRL-lpr mice, and in normals. Anti-Sm precursors were present in a frequency of approximately 1 per 10-30,000 in spleen cell cultures from anti-Sm positive mice, but were undetectable when spleen cells from serologically negative MRL-lpr mice or from normal mice were examined.

Specificity analysis of monoclonal anti-DNA antibodies from B6-lpr/lpr mice.

The binding properties of B6-lpr/lpr anti-DNA monoclonal antibodies were characterized to evaluate the influence of genetic background on the diversity and specificity of lpr-induced autoantibody responses. Six anti-DNA antibodies were produced from fusions with B6-lpr/lpr mice, while another was obtained from a fusion with a B6-+/+ mouse immunized with lipopolysaccharide. Each antibody bound single-stranded DNA in preference to double-stranded DNA, with variation of over 300-fold in relative binding activities.

The influence of the lpr gene on B cell activation: differential antibody expression in lpr congenic mouse strains.

Spontaneous immunoglobulin production in four strains of lpr/lpr congenic mice was investigated to identify genetic interactions in lpr-induced polyclonal B cell activation. Sera were obtained from male and female lpr/lpr mice of the MRL, B6, C3H, and AKR strains as well as controls of +/+ genotypes. Antibody levels were compared at the time of peak response.