REGULATION AND FUNCTION OF PULMONARY SURFACTANT PROTEIN-B

Pulmonary surfactant, a complex mixture of phospholipids and specific associated proteins, reduces the surface tension at the air-liquid int erface of the distal conducting airways and gas exchanging alveoli of the lung. Lipids, primarily neutral and phospholipids, compose approxi mately 90% of the surfactant complex. The remaining 10% of surfactant is composed of at least three surfactant-specific proteins, designated surfactant protein A (SP-A), SP-B, and SP-C. These proteins contribut e to the formation, stabilization, and function of organized surfactan t structures. This article briefly reviews the normal composition and function of pulmonary surfactant and specifically reviews the structur e, function, and regulation of surfactant protein B (SP-B). The recent identification of neonates with refractory respiratory failure due to a genetic absence of SP-B and the study of transgenic mice in which S P-B gene expression has been ablated highlight the importance of the p rotein to surfactant function, synthesis, and metabolism and to the ma intenance of lung function. Gene reconstitution experiments in vitro a nd in SP-B-deficient transgenic mice suggest specific functions for th e amino and carboxyl terminal domains of the protein. SP-B deficiency is a potential target for gene therapy in human patients. (C) 1998 Aca demic Press.