Carbohydrates Occur In Cell Membranes In Lipoproteins

In addition to the lipid of cell membranes (see Chapters 14 and 41), approximately 5% is carbohydrate in glyco-proteins and glycolipids. Carbohydrates are also present in apo B of lipoproteins. Their presence on the outer surface of the plasma membrane (the glycocalyx) has been shown with the use of plant lectins, protein agglutinins that bind with specific glycosyl residues. For example, concanavalin A binds a-glucosyl and a-man-nosyl residues. Glycophorin is a major integral membrane glycoprotein of human erythrocytes and spans the lipid membrane, having free polypeptide portions

Figure 13-16. Structure of W-acetylneuraminic acid, a sialic acid (Ac = CH3— CO —).

outside both the external and internal (cytoplasmic)

surfaces. Carbohydrate chains are only attached to the amino terminal portion outside the external surface (Chapter 41).

30 Day Low Carb Diet Ketosis Plan

30 Day Low Carb Diet Ketosis Plan

An Open Letter To Anyone Who Wants To Lose Up To 20 Pounds In 30 Days The 'Low Carb' Way. 30-Day Low Carb Diet 'Ketosis Plan' has already helped scores of people lose their excess pounds and inches faster and easier than they ever thought possible. Why not find out what 30-Day Low Carb Diet 'Ketosis Plan' can do for you by trying it out for yourself.

Get My Free Ebook

Post a comment