Heparan functions, physiological

In molecules such as heparan sulphate and heparin, there is evidence of a sort of informational content — in the broadest sense — in that some saccharide sequences in these molecules have distinct and diverse physiological functions. These properties are determined by factors such as the distribution of sulphate groups and the relative contents of iduronic and glucuronic acids. If, as seems very likely, all forms of heparan sulphate and heparin share a common pathway of initial polymer assembly, and come to diverge by subsequent modification, it follows that the expression of distinct functions by their oligosaccharide sequences is imposed after the primary polymer is constructed. This applies even if specific modification begins before the polymerisation is complete. The hypothetical primary heparosan sulphate is, therefore, a kind of blank tape upon which sulphotransferases, de-acetylase and 5-epimerase act to imprint the information for specific biological functions. 

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