Biomedical subjects

Alastair Aitken

Publications and source records attributed to Alastair Aitken.

21 records · Page 2Linked to original sources

PubMed2002

Identification of syntaxin-1A sites of phosphorylation by casein kinase I and casein kinase II.

Casein kinases I (CKI) are serine/threonine protein kinases widely expressed in a range of eukaryotes including yeast, mammals and plants. They have been shown to play a role in diverse physiological events including membrane trafficking. CKI alpha is associated with synaptic vesicles and phosphorylates some synaptic vesicle associated proteins including SV2. In this report, we show that syntaxin-1A is phosphorylated in vitro by CKI on Thr21. Casein kinase II (CKII) has been shown previously to phosphorylate syntaxin-1A in vitro and we have identified Ser14 as the CKII phosphorylation site, which is known to be phosphorylated in vivo. As syntaxin-1A plays a key role in the regulation of neurotransmitter release by forming part of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) complex, we propose that CKI may play a role in synaptic vesicle exocytosis.

Amino Acid Sequence↗

PubMed2002

A nonphosphorylated 14-3-3 binding motif on exoenzyme S that is functional in vivo.

14-3-3 proteins play an important role in a multitude of signalling pathways. The interactions between 14-3-3 and other signalling proteins, such as Raf and KSR (kinase suppressor of Ras), occur in a phospho-specific manner. Recently, a phosphorylation-independent interaction has been reported to occur between 14-3-3 and several proteins, for example 5-phosphatase, p75NTR-associated cell death executor (NADE) and the bacterial toxin Exoenzyme S (ExoS), an ADP-ribosyltransferase from Pseudomonas aeruginosa. In this study we have identified the amino acid residues on ExoS, which are responsible for its specific interaction with 14-3-3. Furthermore, we show that a peptide derived from ExoS, containing the 14-3-3 interaction site, effectively competes out the interaction between ExoS and 14-3-3. In addition, competition with this peptide blocks ExoS modification of Ras in our Ras modification assay. We show that the ExoS protein interacts with all isoforms of the 14-3-3 family tested. Moreover, in vivo an ExoS protein lacking the 14-3-3 binding site has a reduced capacity to ADP ribosylate cytoplasmic proteins, e.g. Ras, and shows a reduced capacity to change the morphology of infected cells.

14-3-3 Proteins↗

PubMed2002

Protein identification by in-gel digestion and mass spectrometric analysis.

This protocol details a method for the identification of proteins that have been separated by gel electrophoresis. In-gel digestion of the protein bands with trypsin followed by quadrupole ion-trap or other triple quadrupole mass spectrometry techniques is described. The proteins can be identified by database searching of the mass fingerprint of the intact peptides and of the characteristic fragment masses produced by tandem mass spectrometry.

Animals↗