title: The synaptic protein UNC-18 is phosphorylated by protein kinase C.
abstract: The C. elegans unc-18 encoded protein UNC-18 is implicated in the interactions between synaptic vesicles and presynaptic plasma membrane. To further characterize the neural protein, we investigated the phosphorylation in vitro of the protein expressed in Spodoptera frugiperda Sf21 cells. The UNC-18 protein is selectively phosphorylated by protein kinase C (PKC) but not by casein kinase II and cyclic AMP-dependent protein kinase. The presumed phosphorylation sites determined by manual Edman degradation were serine-2, serine-322, threonine-462 and serine-515, of which the last is highly conserved as a consensus phosphorylation site for PKC in Drosophila and the mammalian homologue. Phosphorylated UNC-18 extracted from C. elegans was also detected, indicating that it has a physiological role in intact nerve terminals. Therefore, the phosphorylation by PKC may play a physiological role in the regulation.
authors.affiliation: Department of Nutrition, School of Medicine, Tokushima University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Sassa
authors.forename: H
authors.initials: H
authors.lastname: Ogawa
authors.forename: M
authors.initials: M
authors.lastname: Kimoto
authors.forename: R
authors.initials: R
authors.lastname: Hosono
mesh_terms: D000595:Amino Acid Sequence; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D015801:Helminth Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D012694:Serine / Q000737:chemistry; D013569:Synapses / Q000737:chemistry*; D013912:Threonine / Q000737:chemistry; D033921:Vesicular Transport Proteins
chemical_list: D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; D015801:Helminth Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; C082636:Unc-18 protein, C elegans; D033921:Vesicular Transport Proteins; D013912:Threonine; D012694:Serine; D011493:Protein Kinase C