Cell Signalling: Gene Expression and Membrane Permeability Flashcards

A comprehensive set of vocabulary flashcards covering steroid hormone mechanisms, specific response elements, and intracellular calcium signaling systems as described in the lecture notes.

Progestagens

A major class of steroid hormones responsible for the maintenance of pregnancy.

Mineralocorticoids

Steroid hormones that increase blood volume and pressure.

Glucocorticoids

Steroid hormones that promote high blood glucose.

Steroid Hormone Receptors

Ligand-activated transcription factor proteins consisting of dimers, each having a hormone-binding domain, a DNA-binding domain, and a promoter-activation domain.

Zinc-finger domain

The second domain of steroid hormone receptors needed for high-affinity DNA binding ($Kd \thicksim 1 \text{ nM}$) to a steroid response element.

Zinc Finger Sequence

The DNA-binding domain structure rich in basic amino acids: $\text{Cys}-\text{X}-\text{X}-\text{Cys}-\text{X}(13)-\text{Cys}-\text{X}-\text{X}-\text{Cys}$.

Specific Response Elements (SREs)

'Labels' identifying genes as targets for transcription factors, consisting of two '1/2 sites' within the DNA sequence.

Histone Acetylases (HATs)

Enzymes recruited by steroid hormone receptors to help unravel chromosomes for gene expression.

Histone Deacetylases (HDACs)

Enzymes removed by steroid hormone receptors to facilitate the initiation or enhancement of transcription.

NRAMP channels

Channels that allow $Fe^{2+}$, a co-factor for many proteins including haem, across the plasma membrane.

GLUT4

A protein that moves glucose into cells by changing the membrane permeability to glucose.

Excitation-contraction coupling

A process first described by Ringer in 1883 where $Ca^{2+}$ is required for signal transduction from nervous stimulation to muscle contraction in the heart.

Hydroxyapatite

Crystals of insoluble calcium phosphate laid onto a collagen-rich matrix representing the mineral form of calcium.

PMCA pump

A Plasma Membrane $Ca^{2+}$ ATPase pump used for the expulsion of calcium from the cell.

SERCA pump

A Sarco-Endoplasmic Reticulum $Ca^{2+}$ ATPase pump used to remove calcium from the cytoplasm by sequestering it into the ER membrane.

IP3 Receptor (IP3R)

A ligand-gated $Ca^{2+}$ channel in the ER membrane that releases calcium ('$Ca^{2+ }$ spark') upon binding Inositol trisphosphate.

Capacitative Ca2+ Entry (CCE)

A biphasic process where a decrease in $[Ca^{2+}]_{ER}$ causes the protein STIM to migrate to the PM and interact with Orai1 and Trpc proteins to trigger extracellular calcium influx.

CRAC

The $Ca^{2+}$ release-activated channel formed at the plasma membrane by the interaction of STIM1, Orai1, and TrpC.

FURA-2

A fluorescent indicator dye used with confocal fluorescence microscopy to monitor and quantitate cytosolic $Ca^{2+}$.

Calcium-induced calcium release

A chain reaction where the activation of IP3R by existing $Ca^{2+}$ starts a '$Ca^{2+}$ wave' throughout the cell.