Description
Product Usage Information
Cells are lysed in a urea-containing buffer, cellular proteins are digested by proteases, and the resulting peptides are purified by reversed-phase solid-phase extraction. Peptides are then subjected to immunoaffinity purification using a PTMScan ® Motif Antibody conjugated to protein A agarose beads. Unbound peptides are removed through washing, and the captured PTM-containing peptides are eluted with dilute acid. Reversed-phase purification is performed on microtips to desalt and separate peptides from antibody prior to concentrating the enriched peptides for LC-MS/MS analysis. CST recommends the use of PTMScan ® IAP Buffer #9993 included in the kit.
Storage
Antibody beads supplied in IAP buffer containing 50% glycerol. Store at -20°C. Do not aliquot the antibody.
Protocol
Available protocols: PTMScan
Background
Apoptosis is a physiological process resulting in a highly regulated, programmed form of cell death that is a normal part of growth and development in multicellular organisms. Aspartic acid-directed cysteine proteases, caspases, are central to the apoptotic mechanism (1). An intrinsic pathway initiates the apoptotic cascade from signals originating within the cell, such as DNA damage, and an extrinsic pathway initiates apoptosis in response to extracellular signals, like FasL. In either case, initiator caspases, such as caspase-8 and 9, begin cleaving downstream substrates that include the effector caspases, such as caspase-3, the most prominent executioner caspase (2,3). These effector caspases amplify the apoptotic cascade to target many critical proteins needed for normal cell function. Apart from its role in developmental biology, the regulation of apoptosis has broad implications for the study of cancer, autoimmune, and infectious diseases among others (4). In the human proteome, there are thousands of known or putative caspase cleavage sites and all are cleaved at an aspartic acid residue, or, in rare cases, a glutamic acid residue. The resultant fragments containing a carboxy-terminal aspartate generally have the XEXD motif with some variation (5). The PTMScan Cleaved Caspase Substrate Motif [DE(T/S/A)D] Kit provides a unique and sensitive method for quantifying hundreds of cleaved caspase substrates, including caspase-3 and 7, NEDD1, HDAC3, MCM4, Notch1, eIF2B, raptor, Bid, Smad6, NFAT90, and PTEN among others.
Alternate Names
caspase; motif
