Disease relevance of RPA3

• Assembly of vaccinia virus: incorporation of p14 and p32 into the membrane of the intracellular mature virus [1].
• There have been only three reported cases of anti-RPA in systemic lupus erythematosus (SLE) and Sjögren syndrome (SjS) [2].
• We report that during activation of the simian virus 40 (SV40) pre-replication complex, SV40 T antigen (Tag) helicase actively loads replication protein A (RPA) on emerging single-stranded DNA (ssDNA) [3].
• Using a polyclonal antibody against recombinant p14, we show here that p14 is also localized to the nucleoli of murine mammary carcinomas and some human breast cancer samples [4].
• We have previously shown that the leader peptide (p14) of the Env-precursor of mouse mammary tumor virus is translocated into the nucleoli of murine T cell lymphomas that harbor this virus [4].

High impact information on RPA3

• Phosphorylation of RPA may play a role in coordinating DNA metabolism in the cell [5].
• In cells, RPA is phosphorylated by DNA-dependent protein kinase when RPA is bound to single-stranded DNA (during S phase and after DNA damage) [5].
• RPA may also have a role in modulating gene expression [5].
• Here, we describe a previously unknown human primary immunodeficiency disorder and provide evidence that the endosomal adaptor protein p14, previously characterized as confining mitogen-activated protein kinase (MAPK) signaling to late endosomes, is crucial for the function of neutrophils, B cells, cytotoxic T cells and melanocytes [6].
• In p14-deficient cells, the distribution of late endosomes was severely perturbed, suggesting a previously unknown role for p14 in endosomal biogenesis [6].

Biological context of RPA3

• RPA3 was mapped to chromosome 7p22 by Southern analysis and PCR amplification of somatic cell hybrids of chromosome 7 as well as fluorescence in situ hybridization [7].
• High-resolution genomic mapping of the three human replication protein A genes (RPA1, RPA2, and RPA3) [7].
• Antibodies prepared against recombinant hRPA3 recognize the native protein and inhibit SV40 DNA replication in vitro [8].
• The hRPA3 cDNA is a 692-base pair sequence that contains an open reading frame encoding a protein of 121 amino acids with a calculated molecular mass of 13.6 kDa [8].
• We have now cloned the 14-kDa subunit (hRPA3) from a HeLa cell cDNA library [8].

Anatomical context of RPA3

• Our data are consistent with a model whereby p32 would become inserted into cellular membranes before being incorporated into the crescents whereas p14 would be posttranslationally associated with the viral outer membrane at a specific later stage of the viral life cycle [1].
• These data suggest that the p14 FAST protein associates with heterogeneous membrane microdomains, a distinct subset of which is defined by cholesterol-dependent Lubrol WX resistance and which may be more relevant to the membrane fusion process [9].
• We analyzed the lipid environment in which the reptilian reovirus p14 FAST protein resides to determine the influence of the cell membrane on the fusion activity of the FAST proteins [9].
• The volume estimates in newborn and p14 mice suggest that the overgrowth in mceph/mceph hippocampus starts between birth and the second week of life [10].
• The observation that COS cells transformed with a cDNA encoding zeta express zeta-p14 supports the former possibility [11].

Associations of RPA3 with chemical compounds

• RPA 3 was inhibited by N-acetyl-D-galactosamine and human alpha-glycoproteins [12].
• From SDS/polyacrylamide-gel-electrophoresis data it was estimated that RPA 1 consisted of two subunits of Mr 34,000, and RPA 3 of two types of subunits (Mr 30,500 and 29,000) [12].
• In transfected cells, p14 was found in both Lubrol WX- and Triton X-100-resistant membrane complexes [9].

Physical interactions of RPA3

• The complex of hRPA14 and hRPA32-(43-171) in turn formed a trimeric complex with the C-terminal region of hRPA70 (amino acids 436-616) [13].

Other interactions of RPA3

• Limited proteolysis of the hRPA14.32 complex defined a core dimer composed of the central region of hRPA32 (amino acids 43-171) and RPA14 [13].
• It is composed of three subunits of 70, 34, and 13 kDa (Rpa1, Rpa2, and Rpa3, respectively) [14].
• Among the nine polypeptides detected by immunoblotting, 38 recognized p14, 17 recognized p8, and 16 recognized p8, and 16 recognized p30 [15].

Analytical, diagnostic and therapeutic context of RPA3

• By analytical ultracentrifugation the Mr values of RPA 1 and RPA 3 were estimated to be 59,000 and 105,000 respectively [12].
• Antigen-capture ELISA with anti-RPA32 mAb, immunofluorescent antinuclear antibodies (ANA) and western blot analysis with purified RPA were also performed [2].
• Topographical mapping of the surface of fusogenic p14-containing liposomes by atomic force microscopy under aqueous conditions revealed that p14 resides almost exclusively in thickened membrane microdomains [9].
• Perfusion images recorded in the acute stage after RFA showed higher compliance to the definitive ablation volume reached after 6 weeks than T2-weighted images, which underestimated the true necrosis size [16].
• For the assessment of the extent of coagulation and for the detection of residual tumor, T1-weighted gradient-echo imaging, T2-weighted spin echo imaging and two different perfusion imaging techniques were performed before, 1 day and 6 weeks after RFA at 1.5 T [16].

References