Protein kinase C regulatory domains: The art of decoding many different signals in membranes

Corbalán-Garcı́a, Senena; Gómez‐Fernández, Juan C.

doi:10.1016/j.bbalip.2006.04.015

Cited by 112 publications

(106 citation statements)

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“…Functionally, although diversity exists (6), the C2 motif typically serves as a reversible membrane-targeting element activated by the binding of multiple Ca 2+ ions (2)(3)(4)(5)7,8). During a cytoplasmic Ca 2+ signal, freely diffusing C2 proteins are activated by Ca 2+ and then dock to specific cellular membranes.…”

Section: Nih-pa Author Manuscriptmentioning

confidence: 99%

“…More generally, these two domains are representative of broader classes of C2 domains that dock to plasma or internal membranes, respectively, where they carry out essential regulatory functions. The goal of the present study is to elucidate the molecular mechanisms by which these two C2 domains are recruited specifically to their target membranes, thereby bringing the other domains of their parent proteins into the vicinity of membrane-associated protein or lipid targets.Protein kinase C isoform α (PKCα 1 ) is a ubiquitous signaling protein and a member of the conventional protein kinase C subfamily of serine/threonine kinases (5,22). The PKCα enzyme regulates a wide array of important pathways ranging from cellular taxis to growth and transformation.…”

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Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca²⁺ Affinity

et al. 2007

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The C2 domain is a ubiquitous, conserved protein signaling motif widely found in eukaryotic signaling proteins. Although considerable functional diversity exists, most C2 domains are activated by Ca 2+ binding and then dock to a specific cellular membrane. The C2 domains of protein kinase Cα (PKCα) and cytosolic phospholipase A 2 α (cPLA 2 α), for example, are known to dock to different membrane surfaces during an intracellular Ca 2+ signal. Ca 2+ activation targets the PKCα C2 domain to the plasma membrane and the cPLA 2 α C2 domain to the internal membranes, with no detectable spatial overlap. It is crucial to determine how such targeting specificity is achieved at physiological bulk Ca 2+ concentrations that during a typical signaling event rarely exceed 1 μM. For the isolated PKCα C2 domain in the presence of physiological Ca 2+ levels, the target lipids phosphatidylserine (PS) and phosphatidylinositol-4,5-bisphosphate (PIP 2 ) are together sufficient to recruit the PKCα C2 domain to a lipid mixture mimicking the plasma membrane inner leaflet. For the cPLA 2 α C2 domain, the target lipid phosphatidylcholine (PC) appears to be sufficient to drive membrane targeting to an internal membrane mimic at physiological Ca 2+ levels, although the results do not rule out a second, unknown target molecule. Stopped-flow kinetic studies provide additional information about the fundamental molecular events that occur during Ca 2+ -activated membrane docking. In principle, C2 domain-directed intracellular targeting, which requires coincidence detection of multiple signals (Ca 2+ and one or more target lipids), can exhibit two different mechanisms: messenger-activated target affinity (MATA) and target-activated messenger affinity (TAMA). The C2 domains studied here both utilize the TAMA mechanism, in which the C2 domain Ca 2+ affinity is too low to be activated by physiological Ca 2+ signals in most regions of the cell. Only when the C2 domain nears its target membrane, which provides a high local concentration of target lipid, is the effective Ca 2+ affinity increased by the coupled binding equilibrium to a level that enables substantial Ca 2+ activation and target docking. Overall, the findings emphasize the importance of using physiological ligand concentrations in targeting studies because super-physiological concentrations can drive docking interactions even when an important targeting molecule is missing.Many signaling pathways are regulated by signaling lipids, membrane proteins, or membranebound complexes associated with the plasma or internal cell membranes. Such membraneassociated signaling components control essential processes, such as cellular movement, growth, gene regulation, metabolism, hormone release, and inflammation. One of the most common regulatory elements in membrane-associated signaling pathways is the C2 domain, a ubiquitous, conserved signaling motif recognized in over 200 mammalian proteins (1). Structurally, the C2 domain motif comprises eight antiparallel β-strands assembled in a β- † F...

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Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca²⁺ Affinity

et al. 2007

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“…Conventional PKCs (cPKCs) are dependent on calcium and diacylglycerol (DAG) for their activity, whereas novel PKCs (nPKCs) are calcium-independent and atypical PKCs (aPKCs) are both calcium-and DAG-independent (Corbalan-Garcia and Gomez-Fernandez, 2006). Despite their functional specificity, all three classes can activate nuclear factor (NF)-kB.…”

Section: Introductionmentioning

confidence: 99%

Protein kinase Cα-CARMA3 signaling axis links Ras to NF-κB for lysophosphatidic acid-induced urokinase plasminogen activator expression in ovarian cancer cells

et al. 2007

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“…They consist of 130 residues and share a common fold composed of two four-stranded β-sheets arranged in a compact β-sandwich connected by surface loops and helices (1)(2)(3)(4). Many of these C2 domains have been demonstrated to function in a Ca 2+ -dependent membrane-binding manner and hence act as cellular Ca 2+ sensors.…”

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Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Guillén

Ferrer-Orta

Buxaderas

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Proteins containing C2 domains are the sensors for Ca 2+ and PI (4,5)P 2 in a myriad of secretory pathways. Here, the use of a freemounting system has enabled us to capture an intermediate state of Ca 2+ binding to the C2A domain of rabphilin 3A that suggests a different mechanism of ion interaction. We have also determined the structure of this domain in complex with PI(4,5)P 2 and IP 3 at resolutions of 1.75 and 1.9 Å, respectively, unveiling that the polybasic cluster formed by strands β3-β4 is involved in the interaction with the phosphoinositides. A comparative study demonstrates that the C2A domain is highly specific for PI(4,5)P 2 /PI (3,4,5)P 3 , whereas the C2B domain cannot discriminate among any of the diphosphorylated forms. Structural comparisons between C2A domains of rabphilin 3A and synaptotagmin 1 indicated the presence of a key glutamic residue in the polybasic cluster of synaptotagmin 1 that abolishes the interaction with PI (4,5)P 2 . Together, these results provide a structural explanation for the ability of different C2 domains to pull plasma and vesicle membranes close together in a Ca 2+ -dependent manner and reveal how this family of proteins can use subtle structural changes to modulate their sensitivity and specificity to various cellular signals.PIP2 | calcium | vesicle fusion C 2 modules are most commonly found in enzymes involved in lipid modifications and signal transduction and in proteins involved in membrane trafficking. They consist of 130 residues and share a common fold composed of two four-stranded β-sheets arranged in a compact β-sandwich connected by surface loops and helices (1-4). Many of these C2 domains have been demonstrated to function in a Ca 2+ -dependent membrane-binding manner and hence act as cellular Ca 2+ sensors. Calcium ions bind in a cupshaped invagination formed by three loops at one tip of the β-sandwich where the coordination spheres for the Ca 2+ ions are incomplete (5-7). This incomplete coordination sphere can be occupied by neutral and anionic (7-9) phospholipids, enabling the C2 domain to dock at the membrane.Previous work in our laboratory has shed light on the 3D structure of the C2 domain of PKCα in complex with both PS and PI(4,5)P 2 simultaneously (10). This revealed an additional lipidbinding site located in the polybasic region formed by β3-β4 strands that preferentially binds to PI(4,5)P 2 (11-15). This site is also conserved in a wide variety of C2 domains of topology I, for example synaptotagmins, rabphilin 3A, DOC2, and PI3KC2α (10,(16)(17)(18)(19). Given the importance of PI(4,5)P 2 for bringing the vesicle and plasma membranes together before exocytosis to ensure rapid and efficient fusion upon calcium influx (20-23), it is crucial to understand the molecular mechanisms beneath this event.Many studies have reported different and contradictory results about the membrane binding properties of C2A and C2B domains of synaptotagmin 1 and rabphilin 3A providing an unclear picture about how Ca 2+ and PI(4,5)P 2 combine to orchestrate the vesi...

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Protein kinase C regulatory domains: The art of decoding many different signals in membranes

Cited by 112 publications

References 254 publications

Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca²⁺ Affinity

Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca²⁺ Affinity

Protein kinase Cα-CARMA3 signaling axis links Ras to NF-κB for lysophosphatidic acid-induced urokinase plasminogen activator expression in ovarian cancer cells

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

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Protein kinase C regulatory domains: The art of decoding many different signals in membranes

Cited by 112 publications

References 254 publications

Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca2+ Affinity

Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca2+ Affinity

Protein kinase Cα-CARMA3 signaling axis links Ras to NF-κB for lysophosphatidic acid-induced urokinase plasminogen activator expression in ovarian cancer cells

Structural insights into the Ca 2+ and PI(4,5)P 2 binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

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Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca²⁺ Affinity

Mechanism of Specific Membrane Targeting by C2 Domains: Localized Pools of Target Lipids Enhance Ca²⁺ Affinity

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1