Summary of Eukaryotic Cell Signalling

Cell Signaling
CELL SIGNALING............................................................................................................................................ 1
TYPES OF SIGNALS AND CELL-CELL SIGNALING............................................................................................... 2
CHEMICAL SIGNALS:..................................................................................................................................................2
PHYSICAL SIGNALS:...................................................................................................................................................2
METHODS OF SIGNALING...........................................................................................................................................2
HORMONES.............................................................................................................................................................2
KEY PLAYERS................................................................................................................................................. 3
INTRACELLULAR RECEPTORS........................................................................................................................................3
Allosteric interactions with small molecules:..................................................................................................3
CELL SURFACE RECEPTORS..........................................................................................................................................3
Cell surface receptors signaling cascade:.......................................................................................................4
Cell surface Receptor Superfamilies:...............................................................................................................4
G-Protein Coupled Receptors (GPCRs):...........................................................................................................4
Key players:............................................................................................................................................................... 4
Action Cascade:......................................................................................................................................................... 4
Features.................................................................................................................................................................... 5
GPCRs as drug targets...............................................................................................................................................5
GPCRs and sensory transduction...............................................................................................................................5
Enzyme Linked receptors:...............................................................................................................................5
RTKs:................................................................................................................................................................6
Ras & Mitogen Activated Protein Kinase (MAPK) cascades:......................................................................................6
Phosphorelay Systems:.............................................................................................................................................6
G-PROTEINS............................................................................................................................................................7
Heterotrimeric G-Protein Mechanism of action.............................................................................................7
SECOND MESSENGERS...............................................................................................................................................8
IP3/DAG Mediated Signal Transduction Pathway:..........................................................................................8
Calcium as a second messenger:....................................................................................................................9
Calcium binding proteins:..........................................................................................................................................9
KINASES..................................................................................................................................................................9
KEY CONCEPTS.............................................................................................................................................. 9
AMPLIFICATION........................................................................................................................................................9
SWITCHING OFF SIGNALS..........................................................................................................................................10
Cholera toxin: (enzyme from cholera bacteria)............................................................................................10
RAS oncogene is the mutant form of RAS:....................................................................................................10
GPCR Desensitization:...................................................................................................................................10
CELL SIGNALING IN PLANTS.......................................................................................................................................11
ESSENTIAL FEATURES OF SIGNAL TRANSDUCTION THAT APPEAR TO BE UNIVERSAL..............................................................11




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, Cell Signaling
Types of signals and cell-cell
signaling
Chemical Signals:
- Hormones
- Metabolites
- Gases
- Pathogen-associated molecular patterns (PAMPs)


Physical Signals:
- Light
- Pressure/touch
- Smell

These are all received by receptors triggering an intracellular signaling cascade which leads
to a response.


Methods of Signaling
- Endocrine signaling:
o Hormones travel to distance targets and bind to receptors in target cells
- Paracrine signaling:
o Secretory cell releases hormone targets adjacent target cell. Very short
- Autocrine signaling:
o Receptor for signaling molecule is on the same cell.
- Plasma-membrane attached proteins:
o Signal is attached proteins that attach to adjacent cells


Hormones
- Steroid hormones:
o Derived from cholesterol
o Regulate metabolism, salt & water balance, inflammatory responses, sexual
function
- Amino acid derivatives:
o Regulate smooth muscle function, blood pressure, cardiac rate & more
- Peptide hormones:
o Regulate processes in al tissues, including release of other hormones
- Bind with high affinity to their receptors




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