High impact information on Nsfl1c

• The finding of a ubiquitin-binding domain in p47 raises the question as to whether the ubiquitin-proteasome system is also involved in membrane fusion events [1].
• Together with its adaptor p47, on the other hand, it regulates several membrane fusion events, including reassembly of Golgi cisternae after mitosis [1].
• Fractionation of cytosol revealed that p97 and its co-factor, p47, constitutes the major fusion activity [2].
• Recruitment of the p47-containing complex onto cell membranes is stimulated by GTP gamma S and blocked by brefeldin A, indicating that, like other coat proteins, its membrane association is regulated by an ARF [3].
• However, p47 is not enriched in preparations of clathrin-coated vesicles [3].

Biological context of Nsfl1c

• We speculate that protein XY40 may be involved in the allocyclic behavior of sex chromosomes during male meiotic prophase [4].
• In contrast to p47, however, Ufd1-Npl4 does not regulate the ATPase activity of p97; nor does a variant of p47 that contains both binding sites but lacks the N-terminal domains [5].
• Importantly, PE-mediated changes in secondary and tertiary structures are exclusively observed when p97 is complexed with p47, which is a prerequisite for membrane fusion [6].
• The ATPase p97 in complex with p47 participates in Golgi cisternae rebuilding after mitosis [6].
• The nucleic acid sequence reveals that XY40 is a novel protein with a few similarities to already known nucleotide sequences [7].

Anatomical context of Nsfl1c

• Biochemical characterization showed that protein XY40 (40 kDa; pI 5.7-5.8) can be extracted from rat pachytene spermatocytes and recovered in particles of 9.5 S with a native molecular mass of approximately 152 kDa [4].
• The ATPase associated with different cellular activities family member p97, associated p47, and the t-SNARE syntaxin 5 are necessary for the cell-free reconstitution of transitional endoplasmic reticulum (tER) from starting low-density microsomes [8].
• Immunocytochemical localization on rat testis cryosections with a XY40-specific monoclonal antibody revealed that the labeling is confined to the axial elements of sex chromosomes [4].
• Phospholipid species act as modulators in p97/p47-mediated fusion of Golgi membranes [6].
• Here we show for the first time that fusion between mitotic Golgi membranes induced by adding cytosol or purified p97/p47 is modulated by PE present in Golgi membranes [6].

Associations of Nsfl1c with chemical compounds

• Like the ubiquitin fold ubiquitin regulatory X (UBX) domain in p47, the Npl4-UBD interacts with p97 via the loop between its strands 3 and 4 and a conserved arginine in strand 1 [5].
• We therefore propose that at physiological conditions PE-induced conformational changes in p97/p47 are relevant in triggering this activity [6].
• Previously it had been shown that p97-mediated reassembly of Golgi cisternae from mitotic Golgi fragments requires p47 which mediates the binding of p97 to a Golgi t-SNARE (soluble N-ethylmaleimide-sensitive factor attachment factor receptor), syntaxin 5 [9].
• RESULTS: Incubation for 24 h in 0.1 mmol/l palmitic acid or a pro-inflammatory cytokine cocktail increased p47( phox ) protein production by 1.5-fold or by 1.75-fold, respectively, in the BRIN BD11 beta cell line [10].
• AIMS/HYPOTHESIS: Acute or chronic exposure of beta cells to glucose, palmitic acid or pro-inflammatory cytokines will result in increased production of the p47( phox ) component of the NADPH oxidase and subsequent production of reactive oxygen species (ROS) [10].

Other interactions of Nsfl1c

• The AAA ATPase p97/VCP interacts with its alternative co-factors, Ufd1-Npl4 and p47, through a common bipartite binding mechanism [5].
• Since the transcripts of both XY40 and Munc18-c show a similar expression pattern, it is tempting to speculate that this common sequence is involved in translation regulation [7].

Analytical, diagnostic and therapeutic context of Nsfl1c

• Purification of binding activities from pancreatic cells by DNA affinity chromatography reveals several distinct proteins ranging in size from 45 to 54 kDa (p45, p47/48, and p54) [11].
• METHODS: Rat pancreatic islets or clonal rat BRIN BD11 beta cells were incubated in the presence of glucose, palmitic acid or pro-inflammatory cytokines for periods between 1 and 24 h. p47( phox ) production was determined by western blotting [10].
• Reverse transcriptase-coupled polymerase chain reaction and Western blotting demonstrate primary cardiac fibroblasts express transcripts and protein for Nox4, p22, p47, and p67 phox [12].

References