Cholesterol and receptor mediate endocytosis

[emminent]

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I thought cholesterol can freely move through the cell membrane w/o any help such as receptor mediate endocytosis. Isn't it peptide hormones such as epinephrine that requires receptor mediated endocytosis?

 

[jwan14]

Yes receptor proteins on the plasma membrane bind to peptide and amino acid hormones such as epinephrine to oftentimes produce secondary messenger such as cAMP and IP3. Cholesterol and other cholesterol derived hormones are fat soluble and can directly diffuse through the membrane and bind to enzymes within the cell or actually even go into the nucleus themselves.

 

[emminent]

Yes receptor proteins on the plasma membrane bind to peptide and amino acid hormones such as epinephrine to oftentimes produce secondary messenger such as cAMP and IP3. Cholesterol and other cholesterol derived hormones are fat soluble and can directly diffuse through the membrane and bind to enzymes within the cell or actually even go into the nucleus themselves.

Alright just making sure cause I'm just rereading cliffs/baron/feralis and saw it stated that cholesterol can be taken in that way from blood.

Cliffs: Proteins that transport cholesterol in blood (low-density lipoproteins, or LDLs) and certain hormones target specific cells by receptor-mediated endocytosis.

Barron: The receptors, carrying the ligand, migrate and cluster along
the membrane, turn inward, and become a coated vesicle that enters the cell. This
is the way cells take in cholesterolfrom the blood; see Figure 4.19.