The first part of this study is titled "Systematic Overview of Membrane Enzymology: Basic Concepts and Terminology" and covers the basic concepts and terminology of cell membrane enzymes in detail. In particular, the structural features, active sites, substrates, cofactors and allosteric sites of integral membrane enzymes are examined. This chapter focuses on how membrane enzymes are anchored to biological membranes, the locations of their active sites and their functional roles, especially metabolic pathways, signal transduction, substance transport and intercellular communication. Additionally, topics such as enzyme kinetics, inhibitors and activators are discussed, and their effects on the biochemical functioning of membrane enzymes and intracellular dynamics are emphasized.

The second chapter, under the title "Molecular Structure and Classification of Membrane Enzymes", examines the molecular structure and functions of different types of proteins in the cell membrane, such as carrier proteins, receptors and enzymes. Active and passive transport systems of carrier proteins, especially the structure and functional mechanisms of important ATPase types such as Na⁺/K⁺ ATPase, are discussed. This chapter details how carrier proteins play critical roles in the transport of substances inside and outside cells and how they transport molecules against concentration gradients by consuming energy through ATP hydrolysis. Receptor proteins are defined as molecular structures that detect signals outside the cell and transform them into intracellular responses. Various types of receptors, such as G-Protein coupled receptors (GPCR) and tyrosine kinase coupled receptors, and how they play important functions in processes such as cell growth, differentiation, and cell cycle are explained. The critical roles of specific enzymes such as adenylyl cyclase and guanylyl cyclase in the production of intracellular second messenger molecules are discussed.

The third chapter examines the “Cellular and Physiological Contexts” of membrane enzymes, particularly their biochemical roles in tissues and organs. In neurons, these enzymes play important roles in synaptic transmission and neurotransmitter metabolism. For example, acetylcholinesterase terminates neurotransmitter signaling by participating in the hydrolysis of acetylcholine in synapses. In liver cells, membrane-bound enzymes such as cytochrome P450 enzymes play important roles in toxin and drug metabolism. It also contains various receptor and co-stimulator molecules in immune system cells, such as MHC molecules that enable the presentation of antigens to T cells and tyrosine kinases that initiate signal transduction. In epithelial cells, enzymes such as carrier proteins and disaccharidases involved in nutrient absorption and electrolyte transport are important. These enzymes play a critical role in the functionality of organs such as the intestines and kidneys by ensuring that nutrients are broken down into absorbable molecules and taken into cells.