The Eleventh Midwest Conference on Endocrinology and Metabol ism in September 1975 brought together a number of leading invest igators in the areas of steroid, peptide, acetylcholine, and cate cholamine hormone receptor studies. This book is based upon the reports of investigations into hormone receptor biochemistry and physiology presented at the Conference as well as on the ensuing discussions. However, many of the manuscripts were written after the Conference. Because of this, the reader will find that some literature references and results of i~vestigations are more up to-date than the Conference date would suggest. Perusal of this and previous volumes will attest to the high quality of this annual conference, due primarily to the efforts of the Planning Committee. We also acknowledge the superb efforts of the staff of Conferences and Short Courses for their assistance in organizing the Conference, and Mrs. Linda Bennett for expert sec retarial assistance in the typing of the book. Last, but certain ly not least, we express our appreciation to the various organiza tions that provided the necessary financial assistance. Leonard R. Forte John M. Franz David M. Klachko vii Contents The Receptor Concept: Prejudice, Prediction, and Paradox. . . . . Oscar M. Hechter Discussion. . . . . . . . . . . . . . 41 DeGroot, Hechter, Campbell, Freed, Barnawell, Morgan, Siegel Nuclear Receptors for Thyroid Hormone . 45 Leslie J. DeGroot 69 Discussion ............ .