Structural basis for the reaction of 3,5,3'-tri-iodothyronine-specific antibodies with thyroxine-containing thyroglobulin.

A series of human autoantibodies against thyroglobulin (Tg) which exhibit different specificities for iodothyronines were studied. The ability of a thyroxine (T4)-containing peptide (T4P) isolated from human thyroglobulin (Tg) to displace [125I]T3 from human T3-specific autoantisera was 11-50 times greater than that of T4 alone. These antisera therefore strongly recognize amino acids adjacent to T4 in the Tg structure.

Exposure of thyroxine residues in human thyroglobulin. Two-site binding studies.

Human thyroglobulin (Tg) could be adsorbed through one of its thyroxine (T4) residues by either of two T4-binding antibodies which had been covalently attached to Sepharose- CL4B . The antibodies used were (i) a purified human autoantibody specific for a T4-containing epitope in human Tg, or (ii) a rabbit antibody raised against T4 conjugated to bovine albumin side chains. Tg adsorbed by either immobilized antibody could then itself adsorb either type of antibody free in solution on to a further T4 residue.

Normal human endometrium in cell culture. III. Mechanism(s) of epithelial polyploidization.

Autoradiography has confirmed previous cytophotometric results showing epithelial polyploid formation to be dependent on DNA synthesis. Polyploidization appears to be largely caused by endoreduplication and perhaps, to a lesser extent, by failure of cytokinesis.

Temporal sequence of hormonal interactions during the prereplicative phase of quiescent cultured 3T3 fibroblasts.

After addition of prostaglandin F2alpha (PGF2alpha) and insulin to quiescent cultured 3T3 fibroblasts a constant lag phase of 15 hr occurs before an increased rate of cellular exit from G1 is observed. The latter process follows first order kinetics, which can be quantified by a rate constant k. The temporal relationship of the interactions of PGF2 alpha, insulin, and hydrocortisone to produce alterations in the rate of exit from G1 was investigated.