Interaction de la thyreostimuline avec ses recepteurs cellulaires: Effet de la phospholipase C sur la fixation et l'activité biologique

Effect of thyroid phospholipids on the interaction of thyrotropin with thyroid membranes.

“…In agreement with reports of others (13)(14)(15), treatment of the membranes with phospholipase A resulted in an increase in TSH binding (Table 4). When the membranes treated with phospholipase A were exposed to acidic phospholipids as described above, there was a dramatic decrease in TSH binding (data not shown).…”

“…In addition, membranes treated with Lubrol PX lost their TSH response, and addition of PtdCho partially restored hormone sensitive adenylate cyclase activity (12). However, our results as well as reports of others (13)(14)(15) We can only speculate on how these acidic phospholipids modulate the ability of the receptor to bind TSH. Current concepts of membrane structure envision membrane receptors as asymmetric with their hydrophobic regions buried in the fluid lipid bilayer.…”

“…Amir et al (15) reported that incubation of bovine thyroid membranes at elevated temperatures caused a loss in TSH receptor sites. They also reported that phospholipase C treatment stimulated TSH binding (15), whereas Haye and Jacquemin (14) found that phospholipase C caused an increase in TSH binding to 6ovine thyroid membranes at low but not high concentrations of…”

“…On the other hand, an important role for phospholipids has been implicated in hormone-responsive adenylate cyclase systems (10)(11)(12)(13)(14)(15). Treatment of thyroid slices and membranes with phospholipases profoundly depressed the stimulation of adenylate cyclase by TSH (10-13) but resulted in enhanced binding of TSH to membranes (13)(14)(15).…”

“…Treatment of thyroid slices and membranes with phospholipases profoundly depressed the stimulation of adenylate cyclase by TSH (10-13) but resulted in enhanced binding of TSH to membranes (13)(14)(15). In order to explore further the relative roles of these two classes of acidic phospholipids on TSH action, we separated the various lipid classes from bovine thyroid glands and studied their ability to affect the binding of bovine TSH to bovine thyroid membranes.…”