Protein Localization and Targeting in Cells

This set of flashcards covers key terminology and concepts related to protein localization and targeting in cells, drawing from detailed lecture notes.

Nuclear Pores

Protein complexes that allow transport of materials into and out of the nucleus.

Golgi Apparatus

An organelle involved in modifying, sorting, and packaging proteins for secretion.

Rough Endoplasmic Reticulum

Type of endoplasmic reticulum studded with ribosomes for protein synthesis.

Nucleus

Cell's information processing and administrative center, containing DNA.

Nuclear Envelope

Double membrane surrounding the nucleus, containing pores for transport.

Ribosomes

Molecular machines that synthesize proteins from amino acids.

Smooth Endoplasmic Reticulum

Type of endoplasmic reticulum involved in lipid synthesis and detoxification.

Secretory Vesicle

Membrane-bound vesicles that transport proteins to the plasma membrane.

Lysosome

Organelles that contain digestive enzymes to breakdown waste materials.

Plasma Membrane

Selective barrier surrounding the cell, controlling movement of substances.

Protein Localization

The process by which proteins are targeted to specific regions or organelles.

Signal Sequence

A short region of amino acids that directs the protein to its destined organelle.

Cytosol

Fluid component of the cytoplasm where ribosome assembly occurs.

Nuclear Localization Signal (NLS)

A sequence that directs proteins to the nucleus.

Ran-GTP

A small GTPase involved in nuclear transport, facilitating protein release.

Nuclear Export Signal (NES)

A signal that directs proteins to exit the nucleus.

Chaperone Proteins

Proteins that assist other proteins in folding correctly.

Translocase of the Outer Membrane (Tom)

Channel that transports proteins into mitochondria.

Translocase of the Inner Membrane (Tim)

Channel for protein transport into the inner mitochondrial membrane.

Peroxisome

Single-membrane organelles involved in lipid metabolism and detoxification.

Mannose-6-Phosphate

Tag for proteins destined for lysosomes, marking them for uptake.

Hydrophobic Amino Acids

Determine whether proteins remain embedded in membranes.

Signal Recognition Particle (SRP)

Complex that recognizes signal sequences and directs ribosomes to the ER.

Cotranslational Targeting

Process where a protein is targeted to the ER while it is being synthesized.

Disulfide Bond Formation

A post-translational modification contributing to protein stability.

KDEL Sequence

A retrieval signal for proteins destined to remain in the ER.

Unfolded Protein Response (UPR)

Cellular response to accumulation of misfolded proteins in the ER.

Proteasome

A complex that degrades unneeded or misfolded proteins.

Polyubiquitination

The process of tagging proteins with multiple ubiquitin molecules for degradation.

Calcium Storage

Role of mitochondria in regulating cellular calcium levels.

Chaperonins

Another type of chaperones that help proteins fold correctly.

Hydrophilic Regions

Regions of proteins that interact favorably with water.

Nucleolus

Region within nucleus where ribosomal RNA is synthesized.

Apoptosis

Programmed cell death, in which mitochondria play a key role.

Trans-Golgi Network (TGN)

Sorting station for proteins before they are delivered to their final destinations.

Vesicular Transport

Mechanism of transporting molecules via membrane-bound vesicles.

Signal Peptidase

Enzyme that cleaves signal peptides off proteins after targeting.

Constitutive Secretion

Process by which cells continuously secrete substances regardless of stimulation.

Regulated Secretion

Conditional secretion of proteins in response to signals.

Basic Amino Acids

Amino acids like lysine and arginine that contribute to NLS.

Glycocalyx

Carbohydrate-rich zone on the cell surface involved in recognition.

Transmembrane Proteins

Proteins that span the entire membrane and are embedded within it.

Endosomes

Membrane-bound compartments that transport proteins within the cell.

Hydrogen Ion Pumps

Proteins that maintain lysosomal acidity for enzyme activity.

Transcription Factors

Proteins that help regulate the transcription of genes.

Gene Expression Regulation

Mechanism that controls the timing and amount of gene expression.

Adenosine Triphosphate (ATP)

Energy currency of the cell produced by mitochondria.

Signal Trafficking

How signals are transported to and from different cellular locations.

RNA-binding Proteins

Proteins that help process and transport RNA.

Endoplasmic Reticulum (ER)

Network of membranes involved in protein and lipid synthesis.

Hydrophobic Domains

Regions of proteins that interact with lipid membranes.

Electrostatic Interactions

Forces between charged amino acids that help stabilize protein structure.

Nuclear Transport Receptors

Proteins that facilitate transport of molecules across the nuclear envelope.

Epigenetic Changes

Alterations in gene expression without changes to the DNA sequence.

Cell Cycle Regulation

Control mechanisms ensuring proper cell division.

Gold particles in Golgi

Visual indicators used in microscopy to study Golgi function.

Cell Signaling Pathways

Routes by which cells communicate and respond to external stimuli.

Signal-Dependent Processes

Processes that require specific signals for activation.