Disease relevance of SAP30

• ORF2, which is expressed only as a 180-kDa fusion protein with ORF1, encodes a single-stranded RNA-binding domain and has the consensus sequence for RNA-dependent RNA polymerases of (+)-strand and double-stranded RNA viruses (pol) [1].
• ORF3 maps in the structural region of the HEV genome and now interacts with the major capsid protein, ORF2, in a post-translational modification-dependent manner [2].
• The phosphorylated form of the ORF3 protein of hepatitis E virus interacts with its non-glycosylated form of the major capsid protein, ORF2 [2].
• Features (ii) and (iii) bring the predicted ORF2 coding strategy of IMNV more in line with that of its closest phylogenetic relative, Giardia lamblia virus, as well as with that of several other members of the family Totiviridae including Saccharomyces cerevisiae virus L-A [3].
• The product of ORF2 has significant homology to the mitochondrial RNA polymerase of yeast and RNA polymerases from bacteriophages [4].

High impact information on SAP30

• The DNA sequence of the nuclear DNA fragment revealed two open reading frames (ORF1 with 1092 bp; ORF2 with 735 bp) on opposite strands, which overlap by 656 bp [5].
• As shown by in vitro mutagenesis, ORF1, but not ORF2, is responsible for complementation of the splice defect [5].
• L1 ORF2 displays an in vivo RT activity similar to that of yeast Ty1 RT in this system and generates pseudogenes with unusual structures [6].
• Deletion analysis of pSC7 revealed the presence of another gene (called ORF2) capable of suppressing the snf3 null mutant phenotype by restoring high-affinity glucose transport and increased low-affinity transport [7].
• Two large antiparallel open reading frames (ORF1 and ORF2) were observed, flanked by potential transcription signals [8].

Biological context of SAP30

• These two reading frames overlap by 130 base pairs and ORF2 is in the -1 reading frame with respect to ORF1 [9].
• Based on their high affinity for the telomeric repeat, we predict that TRF and orf2 play an important role at human telomeres [10].
• Our results support the requirement of this conserved sequence for interaction with ORF2 and also indicate an increase in the strength of the RNA-protein interaction when an additional 44 bases downstream of this 76-nt region were included [11].
• Recombinant plasmids were reduced in copy number relative to k2 with rk2/2 more drastically affected than rk2/6 implying a direct involvement of the ORF2 product in plasmid replication and an indirect maintenance function for the ORF6 gene product [12].
• The amino acid sequences of the largest two ORFs (ORF2 and ORF6) have homology with several DNA polymerases and RNA polymerases, respectively [13].

Anatomical context of SAP30

• Rich in adenine-thymine bases, ORF2 appears to be a homologue of the VAR1 gene which codes for a small ribosomal subunit protein in S. cerevisiae mitochondria [14].

Associations of SAP30 with chemical compounds

• These findings were confirmed using tunicamycin inhibition, point mutants, and deletion mutants expressing only non-glycosylated ORF2 [2].
• ORF2 encodes a 448-amino-acid hydrophobic protein, CrtN, with an M(r) of 50,853 whose deduced sequence is similar to those of phytoene desaturases of other bacteria [15].

Other interactions of SAP30

• Our results demonstrate that Myc-Pho23 co-immunoprecipitates with HA-Rpd3 and HA-Sap30 [16].
• Sap30, another component of this complex, is also required to repress CAR1 expression [17].

Analytical, diagnostic and therapeutic context of SAP30

• Finally, using COS-1 cell immunoprecipitation experiments, we found that the phosphorylated ORF3 protein preferentially interacts with the non-glycosylated ORF2 protein [2].
• Using mutational analysis we have studied dimerization of various truncated versions of the ORF2 capsid protein using the yeast two-hybrid system and supported our findings with in vitro immobilization experiments [18].
• As judged from Southern hybridization and plasmid restriction mapping analyses, these novel hybrids, termed rk2/2 and rk2/6, respectively, carry deletions in their putative DNA (ORF2) and RNA (ORF6) polymerase structural genes with central regions replaced by the input marker DNA [12].
• Sequence analysis showed that the fragments were nearly identical and contained a long open reading frame of 1694 bp (ORF1) and a small ORF of 446 bp (ORF2) within ORF1 on the opposite strand [19].

References