From the Lab of
Doctor Kleifeld Oded
Proteomic profiling of activeproteasomes and intracellular peptidome
The proteasomes are multisubunit,multicatalytic protein complex in eukaryotic cells which degrade misfolded,damaged, or unstructured proteins. Functionally it is divided into a 20Scatalytic core particle and two 19S regulatory particles at both side of 20Sparticle. In eukaryotic cells activeproteasomes exist inthree major types:doubly capped proteasomes – 30S (two 19S on both side of 20S), singly cappedproteasomes – 26S (one 19S on 20S) and 20S proteasomes. The19S recognizes and binds ubiquitin modified target proteins to be degraded byproteasomes. Then after gets unfolded, the target protein is catalyticallycleaved inside the 20S core and released as peptide products. Thecomposition and amount of each of the proteasome active forms are dynamicallycontrolled by the cellular conditions and thought to be directed towardsdifferent types of substrates and to generate different types of products.Unlike the lysosome, where proteases shear proteins up into individual aminoacids, the proteasome just chops proteins into small peptides, with an mean averagesize of 10-12 amino acids length.These peptides can further be processedto single amino acids or possibly be used in many cellular signaling pathways. Thecurrent study is based on to develop a methodology for profiling of active proteasome and the analysis of peptidome generated bydifferent types of proteasomes in yeast cellular system.