Plectin has recently been identified as a widespread and abundant cytoplasmic protein of mammalian cells. In this article the available data on plectin are reviewed, focusing on plectin's occurrence and localization in various cell types and tissues, its biochemical characterization, and its molecular interaction partners. Furthermore, the putative role of this protein has a multifunctional connecting link of the cytomatrix and its structural as well as functional relationship to other cytoskeletal proteins is discussed. It is concluded that plectin is potentially the most versatile crosslinking element of the cytomatrix reported to date.