scholarly journals Acidic phospholipids inhibit the intramolecular association between the N- and C-terminal regions of vinculin, exposing actin-binding and protein kinase C phosphorylation sites

1996 ◽  
Vol 314 (3) ◽  
pp. 827-832 ◽  
Author(s):  
John WEEKES ◽  
Simon T. BARRY ◽  
David R. CRITCHLEY
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Fusion Proteins ◽  
Phosphorylation Site ◽  
Actin Binding ◽  
Tail Region ◽  
Thrombin Cleavage ◽  
Kinase C ◽  
Intramolecular Association ◽  
Acidic Phospholipids

Chick vinculin polypeptides expressed in Escherichia coli as glutathione S-transferase (GST) fusion proteins have been used to identify the sites involved in the intramolecular association between the 90 kDa N-terminal head and the 30 kDa C-terminal tail region of the vinculin molecule. Fusion proteins spanning vinculin residues 1–258 and 1–398, immobilized on glutathione–agarose beads, were shown to bind a C-terminal vinculin polypeptide spanning residues 881–1066 (liberated from GST by thrombin cleavage). However, the C-terminal polypeptide did not bind to a fusion protein spanning residues 399–881 or to itself. Binding was dependent on residues 167–207 within the N-terminal polypeptide, a sequence also essential for talin binding. Conversely, the 90 kDa head polypeptide was shown to bind to residues 1029–1036 in the tail region of vinculin. The association of head and tail was inhibited by acidic, but not neutral, phospholipids. Pre-incubation of vinculin with acidic phospholipids exposed the binding site for F-actin and a phosphorylation site for protein kinase C. The phosphorylation site was located in the tail region of the vinculin molecule. These results raise the possibility that acidic phospholipids play a role in regulating the activity of vinculin and therefore the assembly of both cell–cell and cell–matrix adherens-type junctions.

scholarly journals Identification of an Actin Binding Region and a Protein Kinase C Phosphorylation Site on Human Fascin

1997 ◽  
Vol 272 (4) ◽  
pp. 2527-2533 ◽  
Author(s):  
Shoichiro Ono ◽  
Yoshihiko Yamakita ◽  
Shigeko Yamashiro ◽  
Paul T. Matsudaira ◽  
James R. Gnarra ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphorylation Site ◽  
Actin Binding ◽  
Binding Region ◽  
Kinase C

scholarly journals Phorbol ester treatment increases the exocytic rate of the transferrin receptor recycling pathway independent of serine-24 phosphorylation.

1988 ◽  
Vol 106 (4) ◽  
pp. 1061-1066 ◽  
Author(s):  
T E McGraw ◽  
K W Dunn ◽  
F R Maxfield
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Cell Surface ◽  
Phorbol Ester ◽  
Cho Cells ◽  
Transferrin Receptor ◽  
Phosphorylation Site ◽  
Major Protein ◽  
Kinase C ◽  
Recycling Pathway

In Chinese hamster ovary (CHO) fibroblast cells the protein kinase C activating phorbol ester, phorbol myristate acetate (PMA), stimulates an increase in cell surface transferrin receptor (TR) expression by increasing the exocytic rate of the recycling pathway. The human TR expressed in CHO cells is similarly affected by PMA treatment. A mutant human TR in which the major protein kinase C phosphorylation site, serine 24, has been replaced with the non-phosphorylatable amino acid glycine has been constructed to investigate the role of receptor phosphorylation in the PMA induced up-regulation. The Gly-24-substituted receptor binds, internalizes, and recycles Tf. Furthermore, the altered receptor mediates cellular Fe accumulation from diferric-Tf, thereby fulfilling the receptor's major biological role. The Gly-24 TR behaves identically to the wild-type TR when cells are treated with PMA. Therefore, Ser-24 phosphorylation is not required for the PMA-induced redistribution of the human TR expressed in CHO cells. The increased TR expression on the cell surface after PMA treatment results from an increase in the rate of exocytosis of the recycling receptors. No change in the endocytic rate or the size of the recycling receptor pool was observed. These results indicate that the PMA effect on the TR surface expression may result from a more general perturbation of membrane trafficking rather than a specific modulation of the TR.

scholarly journals The Acidic Region and Conserved Putative Protein Kinase C Phosphorylation Site in Nef Are Important for SIV Replication in Rhesus Macaques

Virology ◽  
1999 ◽  
Vol 257 (1) ◽  
pp. 138-155 ◽  
Author(s):  
Silke Carl ◽  
A.John Iafrate ◽  
Sabine M. Lang ◽  
Christiane Stahl-Hennig ◽  
Eva M. Kuhn ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Rhesus Macaques ◽  
Phosphorylation Site ◽  
Putative Protein ◽  
Kinase C ◽  
Acidic Region ◽  
Putative Protein Kinase

Vinculin but not alpha-actinin is a target of PKC phosphorylation during junctional assembly induced by calcium

1998 ◽  
Vol 111 (23) ◽  
pp. 3563-3571 ◽  
Author(s):  
M. Perez-Moreno ◽  
A. Avila ◽  
S. Islas ◽  
S. Sanchez ◽  
L. Gonzalez-Mariscal
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Actin Binding ◽  
Junctional Complex ◽  
Cell Periphery ◽  
Protein Kinase C Inhibitors ◽  
Kinase C ◽  
Phosphorylation Pattern ◽  
Associated Proteins ◽  
Level 2

The establishment of the junctional complex in epithelial cells requires the presence of extracellular calcium, and is controlled by a network of reactions involving G-proteins, phospholipase C and protein kinase C. Since potential candidates for phosphorylation are the tight junction associated proteins ZO1, ZO2 and ZO3, in a previous work we specifically explored these molecules but found no alteration in their phosphorylation pattern. To continue the search for the target of protein kinase C, in the present work we have studied the subcellular distribution and phosphorylation of vinculin and alpha-actinin, two actin binding proteins of the adherent junctions. We found that during the junctional sealing induced by Ca2+, both proteins move towards the cell periphery and, while there is a significant increase in the phosphorylation of vinculin, alpha-actinin remains unchanged. The increased phosphorylation of vinculin is due to changes in phosphoserine and phosphothreonine content and seems to be regulated by protein kinase C, since: (1) DiC8 (a kinase C stimulator) added to monolayers cultured without calcium significantly increases the vinculin phosphorylation level; (2) H7 and calphostin C (both protein kinase C inhibitors) completely abolish this increase during a calcium switch; (3) inhibition of phosphorylation during a calcium switch blocks the subcellular redistribution of vinculin and alpha-actinin. These results therefore suggest that vinculin phosphorylation by protein kinase C is a crucial step in the correct assembly of the epithelial junctional complex.

Testase 1 (ADAM 24) a plasma membrane-anchored sperm protease implicated in sperm function during epididymal maturation or fertilization

2001 ◽  
Vol 114 (9) ◽  
pp. 1787-1794 ◽  
Author(s):  
G.Z. Zhu ◽  
D.G. Myles ◽  
P. Primakoff
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Acrosome Reaction ◽  
Phosphorylation Site ◽  
Equatorial Region ◽  
Proteolytic Processing ◽  
Mature Sperm ◽  
Kinase C

Plasma membrane-anchored proteases have key roles in cell signaling, migration and refashioning the cell surface and its surroundings. We report the first example of a plasma membrane-anchored protease on mature sperm, testase 1 (ADAM 24). Unlike other studied sperm ADAMs (fertilin (α) and (β), cyritestin) whose metalloprotease domains are removed during sperm development, we found testase 1 retains an active metalloprotease domain, suggesting it acts as a protease on mature sperm. Testase 1 is a glycoprotein (molecular mass 88 kDa), localized to the equatorial region of the plasma membrane of cauda epididymal sperm. Typically, proteolytic removal of the pro-domain is an initial activation step for ADAM proteases. The pro-domain of the testase 1 precursor (108 kDa) is proteolytically removed as sperm transit the caput epididymis to produce processed (mature) testase 1 (88 kDa). Testase 1 is unique among all studied ADAMs in that its proteolytic processing occurs on the sperm plasma membrane instead of at an intracellular site (the Golgi). Using GST-fusion proteins and a synthetic testase 1 C-terminal peptide, we found that the cytoplasmic tail of testase 1 could be phosphorylated in vitro by protein kinase C (PKC). Thus testase 1 apparently has a cytoplasmic PKC phosphorylation site(s). Protein kinase C is known to stimulate other ADAMs' protease activity. Because events of the acrosome reaction include PKC activation, we speculate that testase 1 protease function could be important in sperm penetration of the zona pellucida after sperm PKC is activated during the acrosome reaction.

scholarly journals Invariant Leu Preceding Turn Motif Phosphorylation Site Controls the Interaction of Protein Kinase C with Hsp70

2006 ◽  
Vol 281 (43) ◽  
pp. 32461-32468 ◽  
Author(s):  
Tianyan Gao ◽  
Alexandra C. Newton
Keyword(s):  
Protein Kinase C ◽  
Heat Shock ◽  
Protein Kinase ◽  
Phosphorylation Site ◽  
Insoluble Fraction ◽  
Down Regulation ◽  
Kinase C ◽  
Shock Proteins ◽  
Invariant Residue ◽  
Autophosphorylation Site

Heat shock proteins play important roles in regulating signal transduction in cells by associating with, and stabilizing, diverse signaling molecules, including protein kinases. Previously, we have shown that heat shock protein Hsp70 associates with protein kinase C (PKC) via an interaction that is triggered by dephosphorylation at the turn phosphorylation motif. Here we have identified an invariant residue in the carboxyl terminus of PKC that mediates the binding to Hsp70. Specifically, we show that Hsp70 binds to Leu (Leu-640) immediately preceding the conserved turn motif autophosphorylation site (Thr-641) in PKC βII. Co-immunoprecipitation experiments reveal that mutation of Leu-640 to Gly decreases the interaction of Hsp70 with PKC βII. This weakened interaction between Hsp70 and the mutant PKCs results in accumulation of dephosphorylated PKC in the detergent-insoluble fraction of cells. In addition, the Hsp70-binding mutant is considerably more sensitive to down-regulation compared with WT PKC: disruption of Hsp70 binding leads to accelerated dephosphorylation and enhanced ubiquitination of mutant PKC upon phorbol ester treatment. Last, pulse-chase experiments demonstrate that Hsp70 preferentially binds the species of mature PKC that has become dephosphorylated compared with the newly synthesized protein that has yet to be phosphorylated. Thus, Hsp70 binds a hydrophobic residue preceding the turn motif, protecting PKC from down-regulation and sustaining the signaling lifetime of the kinase.

Effects of calponin on force generation by single smooth muscle cells

1996 ◽  
Vol 270 (5) ◽  
pp. H1858-H1863 ◽  
Author(s):  
A. Horowitz ◽  
O. Clement-Chomienne ◽  
M. P. Walsh ◽  
T. Tao ◽  
H. Katsuyama ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Smooth Muscle Cell ◽  
Contractile Force ◽  
Actin Binding ◽  
Aortic Smooth Muscle ◽  
Kinase C ◽  
Protein Kinase C Epsilon

Although the actin-binding and actomyosin adenosinetriphosphatase (ATPase) inhibitory properties of calponin are well documented in vitro, its function in the smooth muscle cell has not been elucidated. To address this question, we utilized the ferret aortic smooth muscle cell, which shows a protein kinase C-dependent contraction even at pCa (-log [Ca2+]) 9.0 in the absence of a change in myosin light chain phosphorylation. Force was recorded from single, briefly permeabilized cells stimulated via a Ca(2+)-independent pathway by either phenylephrine or the epsilon isoenzyme of protein kinase C. Treatment of stimulated cells with wild-type recombinant calponin reduced steady-state contractile force by 45-60%. When calponin application preceded protein kinase C epsilon treatment, contraction was completely suppressed. On the other hand, calponin phosphorylated at Ser175 or mutant calponin with a Ser175 ⇢ Ala replacement had no effect on contractile force. A peptide corresponding to Leu166-Gly194 of calponin, which included an actin-binding domain but excluded the actomyosin ATPase inhibitory region, was synthesized. Treatment of aortic smooth muscle cells with this peptide triggered a concentration-dependent contraction, presumably by alleviating the inhibitory effect of endogenous calponin. A control peptide with a scrambled sequence of the same residues produced no detectable contractile response. Although other interpretations are possible, these results are consistent with the view that calponin participates in thin filament-mediated regulation of smooth muscle contraction and that it may be part of a Ca(2+)-independent pathway downstream of protein kinase C epsilon.

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