Peroxisome biogenesis conceptually consists of the (a) formation of the peroxisomal membrane, (b) import of proteins into the peroxisomal matrix and (c) proliferation of the organelles. Combined genetic and biochemical approaches led to the identification of 25 PEX genes-encoding proteins required for the biogenesis of peroxisomes, so-called peroxins. Peroxisomal matrix and membrane proteins are synthesized on free ribosomes in the cytosol and posttranslationally imported into the organelle in an unknown fashion. The protein import into the peroxisomal matrix and the targeting and insertion of peroxisomal membrane proteins is performed by distinct machineries. At least three peroxins have been shown to be involved in the topogenesis of peroxisomal membrane proteins. Elaborate peroxin complexes form the machinery which in a concerted action of the components transports folded, even oligomeric matrix proteins across the peroxisomal membrane. The past decade has significantly improved our knowledge of the involvement of certain peroxins in the distinct steps of the import process, like cargo recognition, docking of cargo-receptor complexes to the peroxisomal membrane, translocation, and receptor recycling. This review summarizes our knowledge of the functional role the known peroxins play in the biogenesis and maintenance of peroxisomes. Ideas on the involvement of preperoxisomal structures in the biogenesis of the peroxisomal membrane are highlighted and special attention is paid to the concept of cargo protein aggregation as a presupposition for peroxisomal matrix protein import.

The protein import machinery of the peroxisome consists of many proteins,collectively called the peroxins. By applying the split-ubiquitin technique we systematically tested the pair-wise interactions between the Nub-and Cub-labeled peroxins for the first time in the living cells of the yeast Saccharomyces cerevisiae. We found that Pex10p plays a central role in the protein interaction network by connecting the ubiquitin conjugation enzyme Pex4p to the other members of the protein import machinery. A yeast strain harboring a deletion of PEX3 enabled us to estimate the influence of the peroxisomal membrane on the formation of a subset of the investigated protein-protein interactions.

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Use of social media and the Internet has changed the information-seeking behaviour and exchange of experience and information by patients. Passive observation of such online interaction between patients (social media listening) is conducted in order to understand the burden of the disease, symptom perception, and expectations from a patient perspective. For most conditions, it remains to be established how representative the social media user community is for the overall patient population. In this study, we describe internet and social media use in a population of 570 COPD patients from Germany and Switzerland. This study population is a good representation of the overall patient population in Germany and Switzerland with regards to socioeconomic data. Patients were analyzed in an exploratory fashion whether usage of the Internet to obtain disease-specific information and exchanging on COPD via social media is associated with or is independent from certain socioeconomic criteria. About three-fourths of patients indicated using the Internet to search information about COPD and about a third of patients indicated using social media to exchange with others about their disease. Results indicated that among the patients using the Internet to seek information and among those sharing information via social media, patients with very severe COPD (GOLD stage 4) were overrepresented versus milder forms of the disease. Similarly, patients with more advanced educational background were also overrepresented in the groups using social media and Internet in relation to COPD. Differences in mean age were statistically significant, but surprisingly small between social media users and non-users. No relationship with regards to social media and Internet use for COPD were observed for domiciling situation and sex.