High impact information on PRC1

• It is likely that CPY* entered the ER, was glycosylated, and was then transported back out of the ER lumen to the cytoplasmic side of the organelle, where it was conjugated with ubiquitin and degraded [1].
• PRC1 has sequence homology to the budding yeast anaphase spindle elongation factor Ase1p [2].
• PRC1 is a nuclear protein in interphase, becomes associated with mitotic spindles in a highly dynamic manner during mitosis, and localizes to the cell mid-body during cytokinesis [2].
• Microinjection of anti-PRC1 antibodies into HeLa cells blocked cellular cleavage, but not nuclear division, indicating a functional role for PRC1 in the process of cytokinesis [2].
• These results indicate that the PRC1 missorting mutations are cis-dominant, implying that the mutant forms of proCPY are secreted as a consequence of failing to interact with the sorting apparatus, rather than a general poisoning of the vacuolar protein targeting system [3].

Biological context of PRC1

• To increase the production of CPY in Saccharomyces cerevisiae we have placed its coding region (PRC1) under control of the strongly regulated yeast GAL1 promoter on multicopy plasmids and introduced the constructs into vpl1 mutant strains [4].
• These results suggest that SCM, although not a core component of PRC1, interacts and functions with PRC1 in gene silencing [5].
• We purified a 58 kDa serine protease from culture-supernatant of Pichia pastoris and found that the NH2-terminal amino acid sequence of this protease is closely homologous to that of mature protein of Saccharomyces cerevisiae carboxypeptidase Y (CPY), which is encoded by the PRC1 gene [6].
• The open reading frame of the P. pastoris PRC1 gene consists of 1569 bp encoding a protein of 523 amino acids [6].
• We constructed hypoglycosylated CPY* variants containing one, two or three N-glycans in various combinations and studied their degradation kinetics [7].

Anatomical context of PRC1

• Unlike the situation with a single copy of PRC1 in which newly synthesized CPY is efficiently localized to the vacuole, plasmid-directed overproduction results in secretion of greater than 50% of the protein as the precursor form [8].
• Re-entering the translocon from the lumenal side of the endoplasmic reticulum. Studies on mutated carboxypeptidase yscY species [9].

Associations of PRC1 with chemical compounds

• In this study we analysed two new variants of the mutated yeast carboxypeptidase yscY, CPY*: a carboxy-terminal fusion protein of CPY* and pig liver esterase and a CPY* species carrying an additional glycosylation site at its carboxy-terminus [9].
• Mutant CPY carries an Arg instead of a Gly residue in a highly conserved region, two positions distant from the active-site Ser [10].

Regulatory relationships of PRC1

• The proteinase yscA-triggered maturation process of pro-carboxypeptidase yscY leads to an intermediate mol. wt form of the enzyme which is, however, fully active [11].

Other interactions of PRC1

• Both PEP4 or PRC1 gene disruptions resulted in a lower frequency of mitochondrial DNA escape [12].
• The phenotypic lag in the expression of the carboxypeptidase Y deficiency is abolished by nonsense mutations in either PRC1, the structural gene for carboxypeptidase Y, or PRB1, the structural gene for proteinase B. Models to explain these observations are proposed [13].
• Direct involvement of yscY and ysc alpha was confirmed by sequential disruption of their structural genes PRC1 and KEX1, respectively [14].
• Complete import of CPY into the lumen of the ER requests a new targeting mechanism for retrograde transport of the malfolded enzyme through the Sec61 channel to occur [15].
• High levels of CPY production were obtained by induction of the GAL1 promoter when the cells had left the exponential phase, resulting in a growth-phase-dependent CPY production similar to that of cells with PRC1 under the control of its own promoter [4].

Analytical, diagnostic and therapeutic context of PRC1

• To test this it was exchanged with Ala and Arg by site-directed mutagenesis of the cloned PRC1 gene [16].

References