Mechanisms of Transport of Molecules Between Nucleus and Cytosol

A comprehensive set of flashcards covering the mechanisms of transport of molecules between the nucleus and cytosol, including key terms, definitions, and processes.

Nuclear Pore Complex (NPC)

A large protein complex that spans the nuclear envelope, facilitating the transport of molecules between the nucleus and cytoplasm.

Gated Transport

A mechanism where proteins and RNA molecules move through nuclear pore complexes between the cytosol and nucleus.

Transmembrane Transport

Direct transport of specific proteins across membranes, such as into mitochondria and the endoplasmic reticulum.

Vesicular Transport

Transport of molecules utilizing membrane-enclosed intermediates, like those from the endoplasmic reticulum to the Golgi.

Passive Diffusion

Process by which small ions and metabolites spread through nuclear pore complexes without energy input.

Active Transport

Energy-dependent transport mechanism for larger molecules, such as proteins greater than 50-60 kDa, using carrier proteins.

Nuclear Localization Signals (NLS)

Short amino acid-rich sequences that direct proteins to the nucleus.

Nuclear Export Signals

Signals that guide proteins out of the nucleus to the cytoplasm.

Importins

Nuclear transport receptors that carry proteins into the nucleus, recognizing nuclear localization signals.

Exportins

Transport proteins and RNA molecules out of the nucleus to the cytoplasm.

Ran-GTPase System

A system involving the Ran protein which plays a key role in the nuclear transport processes.

Protein Concentration Gradient

The difference in concentration of importin-cargo complexes between the cytoplasm and nucleoplasm.

FG Repeats

Phenylalanine-glycine repeats found in nucleoporins, forming a gel-like structure that acts as a barrier.

Cytosolic GAP

A protein that converts Ran-GTP to Ran-GDP, influencing nuclear transport.

Nuclear GEF

A protein that converts Ran-GDP back to Ran-GTP, facilitating import and export transitions.

Ribonucleoprotein complexes (RNPs)

Complexes consisting of RNA and proteins that transport RNA molecules through NPCs.

mRNA Transport

The process by which messenger RNA is moved from the nucleus to the cytoplasm, often independent of the Ran system.

Helicase

An enzyme that unwinds DNA or RNA, playing a key role in the processes of replication and transcription.

Histones

Proteins that help package and order DNA into structural units called nucleosomes.

Ribosomal Subunits

The components of the ribosome that are transported from the nucleus to the cytoplasm.

tRNA

Transfer RNA, involved in translating mRNA into proteins by bringing amino acids to the ribosome.

miRNA

MicroRNA, involved in regulating gene expression and is transported from the nucleus to the cytoplasm.

snRNA

Small nuclear RNA, playing a role in the splicing of pre-mRNA.

Import Complex

A complex formed by importins and their cargo proteins that facilitates transport into the nucleus.

Export Complex

A complex formed by exportins and their cargo proteins that facilitates transport out of the nucleus.

Active Transport Mechanism

A mechanism that requires energy to move substances against their concentration gradient.

Transport Traffic

The movement of various molecules through nuclear pore complexes between nucleus and cytosol.

Bidirectional Traffic

The flow of molecules in both directions through nuclear pore complexes.

Nuclear Envelope

The double lipid membrane that surrounds the nucleus, containing nuclear pores.

Nucleoporins

Proteins that make up the nuclear pore complexes, playing critical roles in transport.

Carrier Proteins

Proteins that assist in the active transport of large molecules like proteins across membranes.

Nuclear Import Cycle

The entire process of importing proteins into the nucleus, involving multiple proteins and factors.

Nuclear Export Cycle

The process by which proteins and RNAs are exported from the nucleus to the cytoplasm.

Cytoplasmic Filaments

Structures that extend from the rings of the nuclear pore complex into the cytoplasm.

Nuclear Basket Structure

A structure formed by nuclear filaments that projects into the nucleoplasm from the nuclear pore.

Transport Receptors

Molecules involved in recognizing and binding to cargo proteins for transport across nuclear pores.

Nuclear Expression Signal

A signal that directs proteins to enter the nucleus during processes like T-cell activation.

Intracellular Compartment

Distinct functional areas within a cell, such as the nucleus and cytosol.

Nuclear Filaments

Filaments that attach to nuclear pore complexes, aiding in molecular transport.

Uptake of RNA

The process through which various types of RNA are incorporated into the nucleus or cytoplasm.

Exocytosis

The process of vesicular transport that releases contents outside the cell.

Endocytosis

The process of cellular uptake of molecules from the extracellular space.

Mitochondrial Transport

The mechanisms by which proteins are transported to mitochondria.

Cargo Protein

The molecule, such as a protein or RNA, that is being transported through the nuclear pore.

Nuclear Cytoplasmic Transport

The movement of materials between the nucleus and cytoplasm.

Signal Recognition

The ability of cellular systems to identify and direct specific molecules based on signals attached.

Nuclear Protein Transport

The pathway through which proteins are directed into the nucleus.

Cytosol

The aqueous component of the cytoplasm in which organelles, proteins, and other cell structures float.

Gene Expression Regulation

The control of the timing and rate at which genes are expressed through transport mechanisms.

Protein Affinity Change

The alteration in the binding affinity of transport proteins during import/export cycles.

Exported Ribosome Subunits

Ribosomal components that are synthesized in the nucleus before being transported out.

Cytosolic GTP

Guanosine triphosphate present in the cytosol, crucial for energy transfer during transport.

RNP Assembly

The process of assembling ribonucleoprotein complexes in the nucleus.

Transport Gradient

The difference in concentration of transport molecules across a membrane.

Nuclear Proteins Identification

The process of recognizing proteins that need to be transported to the nucleus.

Ribosomal Protein Association

The binding of proteins to rRNA to form ribosomal subunits in the nucleus.

Transcriptional Regulators

Proteins that regulate the transcription of genes, often transported to the nucleus.

Macromolecular Passage

The transport of large molecules across the nuclear pore complex.

Nucleus

The membrane-bound organelle in cells that contains genetic material.

Signal Transduction Pathways

The series of processes by which a cell responds to signals from its environment.

Transport Mechanisms

Various pathways and systems in place for moving substances across cellular membranes.

Mammalian Cells

A type of eukaryotic cell that has a nucleus and consists of various organelles.

Cellular Compartmentalization

The division of cell functions into distinct areas within the cell.

Signal Mediated Mechanisms

Transport processes that depend on cellular signaling for functionality.

Central Channel of NPC

The main passage within the nuclear pore complex through which molecules are transported.

T-cell Activation

The process whereby T-cells become activated to respond to pathogens, involving nuclear transport mechanisms.

Enzymatic Activity Regulation

Control of enzymatic pathways that can be influenced by nuclear transport of regulatory proteins.

Protein Transport Dynamics

The fluctuations and changes involved in the transport processes between cytoplasm and nucleus.

Macromolecule Transport Rate

The rate at which large molecules pass through the nuclear pores.

Specific Carrier Proteins

Transport proteins that are tailored to bind specific types of cargo for nuclear transport.

Gene Regulation by RNA

The role of RNA molecules in influencing gene expression levels.

Transport Intermediates

Temporary structures that facilitate the transport of molecules between compartments.

Ran Protein Hydrolysis

The process in which GTP-bound Ran is converted to GDP, affecting nuclear transport.

Transport Cycle Dynamics

The stages and transitions that a transport protein undergoes during the transport process.

RNA Processing

The modifications made to RNA molecules before they are exported to the cytoplasm.

Transport Coupling

The coordination of different transport processes to ensure efficient cellular function.

Protein Delivery Systems

Mechanisms through which proteins are directed to their appropriate destinations in the cell.

Cellular Organelles Function

The specific roles played by organelles in maintaining cellular health and function.

KDa

Kilodalton, a unit of molecular weight equivalent to 1,000 daltons.

Biological Macromolecules

Large complex molecules, including proteins and nucleic acids, essential for life.

Cytoplasmic Environment

The surrounding area within the cell cytoplasm, influencing molecular interactions.