Disease relevance of POM121

• The endofluorescent GFP tag had no effect on the distribution of POM121, since the chimerical POM121-GFP fusion protein was correctly targeted to the nuclear pores of both COS-1 cells and neuroblastoma cells [1].
• Antibodies to a 145-kDa minor outer membrane protein (P145) are bactericidal and protect against experimental bacteremia [2].

High impact information on POM121

• Indeed, we demonstrate that POM121 can recruit several nucleoporins, such as Nup62 or Nup358, to ectopic assembly sites [3].
• Nuclear pore complex assembly and maintenance in POM121- and gp210-deficient cells [3].
• So far, POM121 and gp210 are the only known anchoring sites of vertebrate nuclear pore complexes (NPCs) within the lipid bilayer of the nuclear envelope (NE) and, thus, are excellent candidates for initiating the NPC assembly process [3].
• Double knockdowns of gp210 and POM121 in HeLa cells, as well as depletion of POM121 from human fibroblasts, which do not express gp210, further suggest that NPCs can assemble or at least persist in a POM121- and gp210-free form [3].
• NPC turnover measured by fluorescence recovery after photobleaching of POM121 was less than once per cell cycle [4].

Biological context of POM121

• The results suggest that degradation of POM121 may be an important early step in propagation of nuclear apoptosis [5].
• This raises the question of the role of POM121 in ALPC and NPC biogenesis [6].
• However, the in vivo or in vitro addition of known growth factors did not affect P145 tyrosine phosphorylation [7].
• The results showed variable levels of correlation between the methods used for the tumour group (r = 0.915, P less than 0.001 for Ki677 versus P145; r = 0.42, P less than 0.005 for percentage S/G2/M-phase versus P145; r = 0.16, P less than 0.5 for percentage S/G2/M-phase versus AgNOR; r = 0.400, P less than 0.1 for Ki67 versus AgNOR) [8].
• Overall, MAb binding of Ki67 or P145 was seen to be a good indicator of cycling cells, detecting G1-phase cells in addition to S/G2/M-phase cells identified by the other methods used [8].

Anatomical context of POM121

• The nuclear pore complex (NPC) and its relationship to the nuclear envelope (NE) was characterized in living cells using POM121-green fluorescent protein (GFP) and GFP-Nup153, and GFP-lamin B1 [4].
• Assembly of the remaining proteins follows that of the nuclear membranes and occurs in the sequence POM121, p62, CAN/Nup214 and gp210/Tpr [9].
• The POM121 antibodies and antibodies specific for other proteins of the nuclear envelope were used in a comparative study of nuclear apoptosis in staurosporine-treated buffalo rat liver cells [5].
• In order to locate a signal for targeting of POM121 to the nuclear pores, we overexpressed selected regions of POM121 alone or fused to the green fluorescent protein (GFP) in transiently transfected COS-1 cells or in a stably transfected neuroblastoma cell line [1].
• A ratio of bcr-abl protein (P210 or P185) to normal abl protein (P145), the latter is ubiquitously expressed in all blood cells, has been established as a criterion for quantitating bcr-abl levels [10].

Associations of POM121 with chemical compounds

• These findings support a model in which it is POM121 rather than gp210 that defines initial membrane-associated NPC assembly intermediates and which may therefore represent an essential component of the central framework of the NPC [9].
• The 121-kDa pore membrane protein (POM121) is a bitopic integral membrane protein specifically located in the pore membrane domain of the nuclear envelope with its short N-terminal tail exposed on the luminal side and its major C-terminal portion adjoining the nuclear pore complex [1].

Other interactions of POM121

• We have isolated and characterized a novel differentially spliced gene predominantly expressed in the nervous system, which encodes protein isoforms with significant homology to the alpha-actinin protein superfamily, the Caenorhabditis elegans UNC-53 protein and weak homology to the nuclear membrane protein POM121 [11].

Analytical, diagnostic and therapeutic context of POM121

• POM121 degradation occurred surprisingly early and was initiated before nucleosomal DNA degradation could be detected using TUNEL assay and completed before clustering of the nuclear pores [5].
• In immunoblotting, antibody to a 145-kDa protein (P145) was present in protective antisera but not in nonprotective antisera [12].
• Expression of P145 by reactive colonies was confirmed by SDS-PAGE [2].
• Western blot analysis of a gastric carcinoma cell line with P-Tyr antibodies revealed a tyrosine-phosphorylated protein of Mr 145,000 (P145) [7].
• Differences in the VEPs were found between the two groups post-operatively, with the most interesting result being a greater increase in P145 latency in the CA group after rewarming [13].

References