Apolipoprotein C1

Apolipoprotein C-I is a protein component of is_associated_with::lipoproteins that in humans is encoded by the APOC1 is_associated_with::gene.

Function
The protein encoded by this gene is a member of the is_associated_with::apolipoprotein C family. This gene is expressed primarily in the liver, and it is activated when is_associated_with::monocytes differentiate into is_associated_with::macrophages. A is_associated_with::pseudogene of this gene is located 4 kb downstream in the same orientation, on the same chromosome. This gene is mapped to chromosome 19, where it resides within an apolipoprotein gene cluster. Alternatively spliced transcript variants have been found for this gene, but the biological validity of some variants has not been determined.

Apolipoprotein C1 has a length of 57 is_associated_with::amino acids normally found in plasma and responsible for the activation of esterified lecithin cholesterol with an important role in the exchange of esterified cholesterol between lipoproteins and in removal of cholesterol from tissues. Its main function is inhibition of is_associated_with::CETP, probably by altering the is_associated_with::electric charge of HDL molecules.

During fasting (like other is_associated_with::apolipoprotein C), it is found primarily within HDL, while after a meal it is found on the surface of other lipoproteins. When proteins rich in triglycerides like chylomicrons and VLDL are broken down, this apoprotein is transferred again to HDL. It is one of the most positively charged is_associated_with::proteins in the human body.