BIOS 20186 Final Flashcards

Kinase

Phosphorylating protein often in a phosphorylation cascade during cell signaling

nls (abreviation)

Nuclear localization signal —> Sequence of amino acids on a protein that signal it to be transported into the nucleus.

Nuclear Import Receptor

Protein which grabs nls-containing proteins and facilitates their transport into the nucleus. Lets go of the protein by binding to Ran-GTP instead.

Ran

GTPase that is essential in the import of proteins into the nucleus. Active when bound to GTP, and inactive when bound to GDP

Ran-GTP

Active state of Ran. Highly concentrated inside the nucleus. Bind to the nuclear import receptor so it lets go of the cargo protein.

Ran-GDP

Deactivated state of Ran. Highly concentrated in the cytosol.

Ran-GEF

Found inside the nucleus, forces ran to drop the GDP, and pick up a new GTP. (Ran activator)

Ran-GDP

Found in the cytosol, helps Ran undergo its GTPase function to convert Ran-GTP to Ran-GDP. (Ran deactivator)

(Folding) Chaperons

Unfold miss-folding proteins to prevent dangeorus aggregation

Blobel’s Signal Hypothesis

The sequence of amino acids (primary structure) is “necessary and sufficient” to tell the cell where the protein goes

Secretory Pathway

Starts at the ER (synthesis) → Golgi (Packaging/sorting) → Secratory vesicle (Transport from Golgi) → Membrane

ER Protein qualities

1. Folded directly into the membrane (To large & complex when pre-folded). This is done co-translationaly

2. Post-translational modifications (Attaching sugars)

3. Readily formed disulfide bonds (Oxidative environment)

Signal Recognition Particle (SRP)

Recognizes & binds to the ER localization sequence. Pauses/slows down translation until the protein reaches the SRP receptor.

SRP Receptor

Detaches the amino acid sequence from the SRP, and moves the growing peptide chain to the protein translator.

Protein Translocator

Sits in the ER membrane and allows for ER proteins to be synthesized co-transaitonally into the membrane.

The Unfolded Protein Response

Process that maintain proteostasis in the ER. Misfiled proteins become bound to sensors which inhibit protein synthesis. Misfolded proteins will also be degraded via a proteasome.

Cis face of the Golgi

Faces the ER. receives the newly synthesized proteins

Trans face of the Golgi

Sorts and packages proteins. Buds off vesicles for transport.

Constitutive Secretion

Unregulated exocytosis.

Regulated recreation

Requires signal to allow for exocytosis.

The ensomembrance system transports cargo to everywhere in the cell except ____

Mitochondria

Cathrin Coats

Stable coats which form around newly forming vesicles. The attraction between individual clathrin molecules releases energy to stretch the membrane and form a vesicle.

Adaptin

Protein which bind clathrin to the cargo receptors.

Dynamin

GTPase which preforms the cysion of a vesicle using energy of GTP hydrolysis

Clathrin breakdown

Requires energy → ATP hydrolysis (by separate protein)

Rab

GTPase which is activated (GTP-bound) when attached to the correct vesicle membrane.

Tether Protein

Recognizes and binds to a Rab protein to pull a vesicle towards a target membrane.

v-SNARE

SNARE protein on the vesicle which binds to a t-SNARE on the target membrane. This binding releases energy for membrane fusion

t-SNARE

SNARE protein on the target membrane which binds to a v-SNARE on the vesicle. This binding releases energy for membrane fusion

Phagocytosis

When a cell endocyotesis another cell. Same mechanisms as regular endocytosis, but more dramatic.

Autophagy

“Self-eating” → Breakdown of internal cell parts.

Lysosome

Double membrane organelle containing a low pH environment with many acid hydrolyses.

Acid Hydrolases

Enzymes that break down cellular polymers. Are activated in acidic conditions.

Lysosomal proton pump

Pumps protons into the lysosome to maintain low pH. Uses a majority of cellular ATP.Auto

Autophagasome

lipid membrane that grows and forms a closed compartment containing damaged cell parts. The autophagasome must then bind with a lysosome to degrade the cell parts.

mTORC1 (mTOR)

“Mechanistic Target of Rapamycin” Senses flux through the cell. When active, it sits on an active lysosome and promotes growth while repressing autophagy.

Adenylyl Cyclase

Enzyme usually could with the alpha subunit of a GPCR which converts ATP into cyclic AMP

cAMP

“Cyclic AMP”. Made from ATP by adenylyl cyclase, usually acts as a secondary messenger in cell signaling (Activates kinases).

Phosphodiesterases

Family of enzymes that deactivate molecules like cAMP or cGMP.

Glucose & cAMP in the lac operon (prokaryotes)

cAMP gets created in the absence of glucose. Binds to a promoter which helps recruit RNA polymerase for transcription. Still won’t transcribe without the presence of lactose as well.

Glucose & cAMP in Eukartoic nutrient sensing

Glucose binds to a CPCR, sending a signal via cAMP as a secondary messenger to activate transcription of relevant genes.

GCN2

ISR kinase that gets activated when bound to uncharged tRNA (low amino acid concentration in the cell). This phosphorylates elFa/elF2a which then inhibits translation.

ISR Kinase

Kinases that get activated due to stress (Like low nutrient levels). They phosphorylate elF2a to inhibit translation.

elF2a

Promotes translation that delivers Met-tRNA (start) to he 40s subunit of the ribosome.

4E-BP

Gets phosphorylated by mTOR to be released from the 5’ mRNA cap. When bound to the cap, it prevents the ribosome from binding and initiating translation.

Rapamycin

Drug that inhibits mTOR

Active mTOR