tailieunhanh - Báo cáo khoa học: An alternative transcript from the death-associated protein kinase 1 locus encoding a small protein selectively mediates membrane blebbing

Eph receptor tyrosine kinases regulate many important biological pro-cesses. In the present study, we explored the substrate specificity of the EphA4 receptor tyrosine kinase using peptide arrays. We define a consen-sus substrate motif for EphA4 and go on to identify and test a number of potential EphA4 substrates and map their putative site(s) of phosphoryla-tion. | ễFEBS Journal An alternative transcript from the death-associated protein kinase 1 locus encoding a small protein selectively mediates membrane blebbing Yao Lin1 Craig Stevens1 Roman Hrstka2 Ben Harrison1 Argyro Fourtouna1 Suresh Pathuri1 Borek Vojtesek2 and Ted Hupp1 1 Institute of Genetics and Molecular Medicine Cell signalling Unit CRUK p53 SignalTransduction Group University of Edinburgh UK 2 Masaryk MemorialCancer Institute Brno Czech Republic Keywords DAPK-1 ERK membrane blebbing p53 proteolysis Correspondence T. Hupp Institute of Genetics and Molecular Medicine Cell Signalling Unit CRUK p53 SignalTransduction Group University of Edinburgh Edinburgh EH4 2XR UK Fax 44 131 7773542 Tel 44 131 7773583 E-mail Received 14 January 2008 revised 11 March 2008 accepted 14 March 2008 doi Death-associated protein kinase 1 DAPK-1 is a multidomain protein kinase with diverse roles in autophagic apoptotic and survival pathways. Bioinformatic screens were used to identify a small internal mRNA from the DAPK-1 locus named s-DAPK-1 . This encodes a 295 amino acid polypeptide encompassing part of the ankyrin-repeat domain the P-loop motifs part of the cytoskeletal binding domain of DAPK-1 and a unique C-terminal tail extension not present in DAPK-1. Expression of s-DAPK-1 mRNA was detected in a panel of normal human tissues as well as primary colorectal cancers indicating that its expression occurs in vivo. s-DAPK-1 gene transfection into cells produces two protein products one with a denatured mass of 44 kDa and a smaller product of 40 kDa. Double alanine mutation of the C-terminal tail extension of s-DAPK-1 Gly296 Arg297 prevented production of the 40 kDa fragment suggesting that the smaller product is generated by in vivo proteolytic processing. The s-DAPK-1 gene cannot substitute for full-length DAPK-1 in an mitogen-activated protein kinase kinase extracellular signal-regulated kinase-dependent apoptotic transfection assay.