Vol 56, No 5 (2005)
Original paper
Published online: 2006-05-28
The cysteine bonding in TSH receptor and it function in autoantibodies recognition
Endokrynol Pol 2005;56(5):766-772.
Abstract
The majority of epitopes for TSH receptor (TSHR)
stimulating autoantibodies are clustered around the Nterminal
region of the TSH receptor. The characteristic
feature of this region is the presence of four cysteine
residues. It was proposed that cysteines in positions 29
and 41 in the receptor are connected by disulfide bonds
and they are the target for receptor stimulating antibodies.
The present study was aimed to check this possibility.
The synthetic peptides: peptide corresponding to the part
of TSHR containing the above 29-41 cysteine bond, the
peptide similar to this peptide but without disulfide bond
and the control peptide, containing sequence absent in the
receptor were used for rabbit immunization. The thyroid
status of all immunized rabbits was the same. Rabbits
immunized with peptides related to TSHR generated
antisera reactive with TSHR in immunoenzymatic assay.
To check specificity of this reaction the influence of the
peptides and the antisera on TSH binding to the receptor
in competitive assay (TRAK) and their influence on
adenylate cyclase activity were studied. It was found
that neither synthetic peptides nor antiserum from any
rabbit influenced TSH binding to the receptor in TRAK. In
contrast low, but significant adenylate cyclase stimulating
activity was noticed for antisera from two of six rabbit
immunized by peptide containing the disulfide bond. We
concluded that such a bond between cysteine residues
29 and 41 are present in TSHR in the site of stimulating
antibodies epitope.
Keywords: TSH receptorpeptidesantibodies
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