Protein Transport – Protein Functions

by Kevin Ahern, PhD

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    00:00 the catalytic process and this is a very magical part of enzymes, as it were.

    00:02 Proteins also play very important functions in transporting and this transport can happen at several levels. The transport can happen first of all, at the level of the organism, and that's what I want to talk about first, but we can also remember the transport happens at the level of the individual cell. Now at the level of the organism, it's important for molecules to move around the body, and the molecules don't necessarily move naturally by themselves. Some really good examples are for example the lipids. The lipids tend to be fairly nonpolar molecules, so if we think of fat for example, or fat-soluble vitamins, or cholesterol, all of these molecules are very insoluble in water. Our blood stream however, is full of water. So how is it that these molecules move through our body? Well it turns out that the primary way that these nonpolar molecules move through our body are through complexes called lipoprotein complexes. The lipoprotein complexes, one of which I've depicted on the screen on the right, surround the insoluble fat and lipid material with water soluble materials. So you can see for example, there are several proteins in the circle that's here. You see the apo B, apo C, apo E, all there, and they are together with some phospholipids that allow the outside to be polar and interact with water, while on the inside, the nonpolar portions are all interacting with the lipids that are nonpolar.

    01:37 This little capsule, as it were, travels in the blood stream freely to target places tissues that will then absorb these materials and use them as appropriate. The image depicted on the screen is that of a chylomicron. A chylomicron is the first lipoprotein complex that these molecules encounter upon eating a fatty diet for example. So when you eat a diet that has fat molecules and these other molecules in it, they are absorbed first into chylomicrons.

    About the Lecture

    The lecture Protein Transport – Protein Functions by Kevin Ahern, PhD is from the course Biochemistry: Basics.

    Included Quiz Questions

    1. The turnover number describes how fast enzymes are made and destroyed
    2. The Koshland mechanism describes how enzyme flexibility enables catalysis
    3. The binding of the substrate induces structural changes in enzymes, leading to catalysis
    4. Reaction products induce additional structural changes in the ES complex
    1. They include complexes like LDLs and HDLs
    2. They do not move ions
    3. In the bloodstream, they carry polar compounds within a non-polar outer shell
    4. They only work outside of cells

    Author of lecture Protein Transport – Protein Functions

     Kevin Ahern, PhD

    Kevin Ahern, PhD

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