Tertiary Structure Assembly of Basic Units

How are the basic units arranged to form the macrostructure of the larger mucins Evidently, because of the nature of the degradation products of pronase digestion, the linkage is by way of the naked peptide regions. 

It was originally suggested that the links between the basic units are through intermolecular disulfide bridging between cysteine residues in the naked end r ons. Reduction of mucins by thiols produced the M, 500,000 forms (see, for example. Refs. 26 and 36). However, Creeth observed a variety of forms in the 0.5-2.0 X 10 r on, and subsequent observations on cervical and other mucins by Carlstedt and Sheehan S yielded, in the presence of guanidine hydrochloride (Gu-HQ), species having forms M, 2 X 10 which they referred to as 

Basic unit basic mucin building block, M, S X I O glycosylated central-core r on plus 

T-domain product remaining after treatment of mucin with proteases equivalent to a basic 

Subunit product remaining after reduction of mudn by thiols, whatever form this may take 

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