Péter Friedrich

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The structural clues of substrate recognition by calpain are incompletely understood. In this study, 106 cleavage sites in substrate proteins compiled from the literature have been analyzed to dissect the signal for calpain cleavage and also to enable the design of an ideal calpain substrate and interfere with calpain action via site-directed mutagenesis.(More)
Calpains, the Ca2+-dependent intracellular proteinases, are involved in the regulation of distinct cellular pathways including signal transduction and processing, cytoskeleton dynamics, and muscle homeostasis. To investigate the evolutionary origin of diverse calpain subfamilies, a phylogenetic study was carried out. The topology of the calpain phylogenetic(More)
Intrinsically unstructured proteins (IUPs) are devoid of extensive structural order but often display signs of local and limited residual structure. To explain their effective functioning, we reasoned that such residual structure can be crucial in their interactions with their structured partner(s) in a way that preformed structural elements presage their(More)
Rat brain microtubule-associated protein MAP1B has been tested as a substrate for Ser/Thr protein phosphatases (PP). The dephosphorylation reactions were followed by specific antibodies recognizing phosphorylated and phosphorylatable epitopes. One set of phosphorylation sites on MAP1B are referred to as mode I sites, and their phosphorylation is presumably(More)
Intrinsically unstructured proteins (IUPs) lack a well defined three-dimensional structure under physiological conditions. They constitute a significant fraction of various proteomes, but only a handful of them have so far been identified. Here we report the development of a two-dimensional electrophoresis technique for their de novo recognition and(More)
BACKGROUND Polyomavirus BK virus (BKV) infection represents a serious complication leading to BKV-associated nephropathy (BKVAN) and subsequent kidney graft loss in up to 10% of transplant patients. Cellular immunity is known to play a crucial role in the control of BKV replication. However, the knowledge on the BKV-T-cell response is limited: only two (VP1(More)
Mammalian ubiquitous micro- and m-calpains, as well as their Drosophila homologs, Calpain A and Calpain B, are Ca(2+)-activated cytoplasmic proteases that act by limited proteolysis of target proteins. Calpains are thought to be part of many cellular signaling pathways. These enzymes, however, require such high Ca(2+) concentration for half-maximal(More)
Calpains are calcium-dependent proteases believed to participate in calcium-regulated signal pathways in cells. Ubiquitous calpains as well as tissue-specific calpains have been found in vertebrates. We isolated cDNA clones for a highly tissue-specific calpain gene from Drosophila melanogaster, CalpA, at 56C-D on the second chromosome. The expression of the(More)
We have cloned a Drosophila homolog of the membrane fusion protein CDC48/p97. The open reading frame of the Drosophila homolog encodes an 801 amino acid long protein (TER94), which shows high similarity to the known CDC48/p97 sequences. The chromosomal position of TER94 is 46 C/D. TER94 is expressed in embryo, in pupae and in imago, but is suppressed in(More)
Calpain activity of nerve growth factor (NGF)-induced rat pheochromocytoma (PC12) cells shows a transient diminution in the early phase of differentiation. Calpain activity can be further decreased by a cell-permeable calpain inhibitor, calpeptin, which enhances the effect of NGF by stimulating neurite elongation. The number of neurites sprouted by one cell(More)