Protein Sorting etc Flashcards
Eukaryotic cells have elaborate mechanisms for protein packaging and delivery to specific sites within the cell or to the cell membrane for secretion. What are some examples of this?
Endoplasmic reticulum (ER) and Golgi apparatus, vesicular transport, protein sorting signals. etc
What is ER?
The ER is a network of interconnected membranes that plays a major role in protein synthesis and folding.
Proteins that are destined for secretion or membrane localization are synthesized and folded in the ER.
How does this involve the golgi?
From the ER, these proteins are transported in vesicles to the Golgi apparatus, which is a series of stacked membranes.
Within the Golgi, proteins undergo post-translational modifications, such as glycosylation, phosphorylation, and sulfation, which help determine their final destinations and functions.
What is vesicular transport?
Vesicles are small membrane-bound sacs that bud off from one membrane compartment and fuse with another.
What are vesicles involved with?
In intracellular transport of proteins, including packaging and delivery.
Vesicles can bud off from the ER and Golgi, carrying cargo proteins, and then fuse with other membranes within the cell or fuse with the cell membrane for secretion.
What is the KDEL retrograde system?
is a cellular mechanism that plays a role in the retrieval of endoplasmic reticulum (ER) resident proteins from the Golgi apparatus back to the ER.
Why is it important?
It is an important cellular mechanism that helps maintain the integrity and proper function of the ER by ensuring that ER resident proteins are retrieved from the Golgi apparatus and returned to the ER for their appropriate localization and activity.
What are the basics of protein folding at thermodynamic level?
Enthalpy (ΔH), Entropy (ΔS), Gibbs free energy (ΔG), Folding funnel concept and role of water.
What is Enthalpy (ΔH)?
Enthalpy refers to the heat energy changes that occur during protein folding.
It includes various interactions between atoms and groups within the protein, such as hydrogen bonds, van der Waals interactions, electrostatic interactions, and covalent bonds.
Would it be exothermic or endo?
Both in this situation, in terms of enthalpy, depending on their strength and stability.
Favorable enthalpic contributions typically arise from the formation of stable secondary structures, such as α-helices and β-sheets, as well as from the packing of hydrophobic residues in the protein core.
What is Entropy?
Entropy refers to the measure of disorder or randomness in a system. In the case of protein folding, the polypeptide chain in its unfolded state has a high degree of conformational freedom, resulting in high entropy.
What happens when the protein folds into its native structure during entropy?
The conformational freedom of the protein becomes more restricted, leading to a decrease in entropy.
This decrease in entropy is usually unfavorable for protein folding.
What is Gibbs free energy?
Gibbs free energy is the thermodynamic potential that determines whether a process is spontaneous or not.
In the case of protein folding what is Gibbs free energy?
In the case of protein folding, the change in Gibbs free energy (ΔG) is a combination of the changes in enthalpy (ΔH) and entropy (ΔS), and is given by the equation ΔG = ΔH - TΔS, where T is the temperature in Kelvin.
A negative ΔG indicates a spontaneous process, while a positive ΔG indicates a non-spontaneous process.
