Disease relevance of LHP1

• Immunoprecipitation of Lhp1p fused to Staphylococcus aureus protein A resulted in coprecipitation of both U3-3'I and -II [1].

High impact information on LHP1

• Although maturation of the mutant pre-tRNA(Ser)CGA requires Lhp1p, introduction of a second mutation that restores base pairing eliminates the requirement [2].
• The phenotypes of gcd10 mutants were suppressed by high-copy-number IMT genes, encoding initiator methionyl tRNA (tRNAiMet), or LHP1, encoding the yeast homolog of the human La autoantigen [3].
• Lhp1p is also required for efficient aminoacylation of two wild-type tRNAs when yeast are grown at low temperature [4].
• Intragenic suppressor mutations that disrupt the misfolded helix or strengthen the correct helix alleviate the requirement for Lhp1p, providing evidence that the anticodon stem misfolds in vivo [4].
• A mutation in a core protein of the spliceosomal snRNPs, Smd1p, causes yeast cells to require the La protein Lhp1p for growth at low temperatures [5].

Biological context of LHP1

• Lhp1 ribonucleoprotein complexes were immunoprecipitated and bound RNAs were examined by hybridization to whole-genome microarrays that include >6,000 ORFs, documented noncoding RNAs, and the intervening intergenic regions [6].
• To broaden our understanding of the function of the La homologous protein (Lhp1) in Saccharomyces cerevisiae, we have taken a genomics approach [6].
• Moreover, Lhp1p, a protein binding RNA polymerase III transcripts, was required to stabilize the mutant tRNAs [7].
• Sxm1p and Lhp1p represent the karyopherin and a cognate substrate of a unique nuclear import pathway, one that operates upstream of a major pathway of pre-tRNA maturation, which itself is upstream of tRNA export in wild-type cells [8].
• At low temperatures, Lhp1p becomes essential for the accumulation of U4/U6 snRNPs and for cell viability [5].

Associations of LHP1 with chemical compounds

• To dissect the role of phosphorylation in La protein function, we used mass spectrometry to identify three sites of serine phosphorylation in the S. cerevisiae La protein Lhp1p [9].
• Mutant versions of Lhp1p, in which each of the serines was mutated to alanine, were expressed in yeast cells lacking Lhp1p [9].

Other interactions of LHP1

• Indirect immunofluorescence microscopy reveals that although Lhp1p is primarily localized to the nucleus, Sro9p is cytoplasmic [10].
• A mutation within the Sm motif of Lsm8p causes Saccharomyces cerevisiae cells to require the La protein Lhp1p to stabilize nascent U6 snRNA [11].
• Demonstrating the validity of this approach, associations with previously known Lhp1p-associated RNAs were detected and associations with additional noncoding RNAs, including multiple tRNAs and small nucleolar RNAs, were revealed [6].
• GCD14p, a repressor of GCN4 translation, cooperates with Gcd10p and Lhp1p in the maturation of initiator methionyl-tRNA in Saccharomyces cerevisiae [12].
• The impaired pre-tRNA processing seen on Lsm depletion is not, however, due solely to reduced Lhp1p association as evidenced by analysis of lhp1-Delta strains depleted of Lsm3p or Lsm5p [13].

Analytical, diagnostic and therapeutic context of LHP1

• Identification of Lhp1p-associated RNAs by microarray analysis in Saccharomyces cerevisiae reveals association with coding and noncoding RNAs [6].
• Northern blotting revealed no effects of Lhp1p phosphorylation status on either pre-tRNA maturation or stabilization of nascent RNAs [9].
• Using two-dimensional gel electrophoresis, we determined that we had identified and mutated all major sites of phosphorylation in Lhp1p [9].

References