Biochemical Actions of Hormones, Volume XII is a compendium of papers discussing aspects of molecular biology with regard to hormone action and to certain hormone receptors. One paper discusses the different approaches and strategies that are used in determining the amino acid sequence. The paper also describes the structural organization of polyprotein precursors such as the peptide chemistry approach or the nucleic acid approach. Another paper investigates the regulation of prolactin biosynthesis by peptide hormones as a model for peptidergic regulation of gene expression. The paper defines in detail which components of the biosynthetic machinery are being regulated by the polypeptide hormones. One paper also analyzes the molecular biology of the metallothioneins, focusing on the glucocorticoid regulation of metallothioneins genes. Experiments show that when the mouse MT-I gene is activated in lymphoid cells, or transferred to other cells, it still retains information needed in metal-regulated expression, though glucocorticoids can no longer regulate the same gene. Other papers discuss the purification and properties of the nerve growth factor receptor, and the thyrotropin receptor. Micro-biologists, biochemists, molecular biologists, cellular biologists, endocrinologists, and scientists involved in cell research will find this collection valuable.