What are intrinsic and extrinsic proteins?

Answer 1

intrinsic

Of or relating to the essential nature of a thing; inherent.

Anatomy. Situated within or belonging solely to the organ or body part on which it acts. Used of certain nerves and muscles.

[Middle English intrinsique, inner, from Old French intrinseque, from Late Latin intrīnsecus, inward, from Latin, inwardly.]

Situated entirely within, or pertaining exclusively to, a part.

i. factor - see intrinsic factor.

i. host determinants - characteristics peculiar to the host that affect the spread and occurrence of a disease.

i. nerve - some evidence exists for the presence of autonomous nerves, without connection to the CNS, in the adventitia of small arteries and arterioles.

i. pathway, i. system - see coagulation pathways.

i. protein - see membrane proteins.

extrinsic

Not forming an essential or inherent part of a thing; extraneous.

Originating from the outside; external.

[Latin extrīnsecus, from outside : exter, outside; see exterior + -im, adv. suff. + secus, alongside.]

Of external origin.

e. allergic alveolitis - see hypersensitivity pneumonitis.

e. factor - see extrinsic factor.

e. incubation period - the period between infection of the arthropod insect vector and the vector's ability to infect the next vertebrate host.

e. pathway - see coagulation pathways.

e. protein - see membrane proteins.

Answer 2

Intrinsic proteins, aka 'integral' proteins, are bound within the plasma membrane of a cell. All integral proteins have at least one region called the 'transmembrane domain', which is composed of mostly all hydrophobic amino acids, and thus can penetrate the lipid bilayer of the plasma membrane. Many integral proteins have several transmembrane domains that snake in and out of the plasma membrane, with hydrophilic domains protruding both into the cytoplasm of the cell, and the extracellular environment. The strict definition of what makes a protein integral, is that the plasma membrane must be disrupted for the protein to be released.

Extrinsic proteins are also called 'peripheral' proteins. These are also associated with membranes, but they do not penetrate the mebrane itself. They are usually bound to integral proteins by non-covalent bonds, and can therefore be extracted from the membrane without destroying it (using some kind of chemical wash). There are also 'anchoring' proteins which do actually penetrate the membrane, but only slightly

Answer 3

I think in the neurotic translated area.