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Most newly synthesized peroxisomal matrix proteins are targeted to the organelle by Pex5p, the peroxisomal cycling receptor. According to current models of peroxisomal biogenesis, Pex5p interacts with cargo proteins in the cytosol and transports them to the peroxisomal membrane. After delivering the passenger protein into the peroxisomal matrix, Pex5p returns to the cytosol to catalyze additional rounds of transportation. Obviously, such cyclic pathway must require energy, and indeed, data confirming this need are already available. However, the exact step(s) of this cycle where energy input is necessary remains unclear. Here, we present data suggesting that insertion of Pex5p into the peroxisomal membrane does not require ATP hydrolysis. This observation raises the possibility that at the peroxisomal membrane ATP is needed predominantly (if not exclusively) downstream of the protein translocation step to reset the Pex5p-mediated transport system.Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and post-translationally imported into the organelle. The vast majority of these proteins possess the so-called peroxisomal targeting sequence 1 (PTS1), 1 a C-terminal tripeptide complying to the consensus sequence S/A/C-K/R/H-L/M (1-4). These PTS1-containing proteins are specifically targeted to the organelle matrix by Pex5p, the PTS1 receptor (5-9).According to current models of peroxisomal biogenesis, the Pex5p-mediated process of protein import can be divided into four steps. In the first step, newly synthesized PTS1-containing proteins interact with Pex5p in the cytosol. This protein-protein interaction involves the PTS1 signal on one side and the tetratricopeptide repeats domain of Pex5p on the other. The Pex5p-cargo protein complex is then recognized by the so-called docking machinery present in the peroxisomal membrane. Somewhere after this event, the PTS1-containing protein is released into the peroxisomal matrix. Finally, Pex5p is recycled back to the cytosol to catalyze additional rounds of transportation (reviewed in Refs. 10 -12).One obvious property of such cyclic mechanism is that it needs some form of energy input to function, and indeed, basically all the studies addressing this issue are unanimous in this respect: protein import into the peroxisomal matrix requires hydrolysis of ATP (13-21). However, the precise step(s) of this import pathway where energy input is necessary has not been firmly established. For instance, it is generally accepted that the step of protein translocation across the peroxisomal membrane requires ATP hydrolysis. Such conclusion derives from the fact that ATP depletion or the inclusion of non-hydrolysable ATP analogues in the several experimental systems used result in an inhibition of the peroxisomal import process. However, the possibility that recycling of Pex5p back to the cytosol is an ATP-dependent event and the rate-limiting step in all this process was never considered. In this scenario, inhibition of peroxisomal protein import by lack of ATP would resu...

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The urinary nerve growth factor-to-creatinine and brain-derived neurotrophic factor-to-creatinine ratios are increased in patients with overactive bladder. These findings may have pathophysiological and clinical implications.

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Symptomatic improvement of bladder pain syndrome/interstitial cystitis persists in a repeated intratrigonal injection program of 100 U onabotulinum toxin A. Time to request re-treatment remained stable. Adverse events were mild, without voiding dysfunction requiring intermittent catheterization.