Function of the ER:

most eukaryotic cells is to sequester Ca2+ from the cytosol (High concentration of Ca2+-binding proteins in the ER facilitates Ca2+ storage)

TLS Online TPP Program

#Id: 5792

#Unit 7. System Physiology – Animal

When the peroxidase system is blocked or when it is hereditarily absent from the cells, the rate of formation of thyroid hormones falls to zero

TLS Online TPP Program

#Id: 5793

#Unit 7. System Physiology – Animal

“Organification” of Thyroglobulin- Iodination of tyrosine and formation of the thyroid hormones

TLS Online TPP Program

#Id: 5794

#Unit 7. System Physiology – Animal

Tyrosine is first iodized to monoiodotyrosine and then to diiodotyrosine. Then, more and more of the iodotyrosine residues become coupled with one another

TLS Online TPP Program

#Id: 5795

#Unit 7. System Physiology – Animal

TLS Online TPP Program

#Id: 5796

#Unit 7. System Physiology – Animal

The major hormonal product of the coupling reaction is the molecule thyroxine (T4), which is formed when two molecules of DIT are joined together; the thyroxine then remains part of the thyroglobulin molecule.

TLS Online TPP Program

#Id: 5797

#Unit 7. System Physiology – Animal

Iodinated Tyrosines (MIT and DIT) are deiodinated by a microsomal iodotyrosine deiodinase, to recover iodine and bound tyrosines and recycle them for additional rounds of hormone synthesis.