Showing papers by "Manfred Sumper published in 1993"
TL;DR: Evidence is presented for the existence of a novel mechanism of signal amplification operating within the extracellular matrix of this multicellular organism.
Abstract: The sex-inducing pheromone of Volvox carteri is a glycoprotein that triggers development of males and females at a concentration below 10(-16) M. Evidence is presented for the existence of a novel mechanism of signal amplification operating within the extracellular matrix of this multicellular organism. A family of 70 kDa matrix glycoproteins denoted pherophorins bear a C-terminal domain being homologous to the sex-inducing pheromone. Under the influence of the pheromone, this domain is liberated by highly specific proteolysis.
47 citations
01 Jan 1993
TL;DR: A comparison of the corresponding S-layer protein structures should give hints on how adaptation to high salt conditions works and are considered ideal model systems to study the adaptation of protein structures to unfavourable conditions.
Abstract: The first procaryotic glycoprotein was discovered in the S-layer of halobacteria of the genus Halobacterium by Mescher and Strominger (1976). Saturated sodium chloride solutions are the natural habitat of these rod-shaped and flagellated archaeobacteria. The original finding was that the halobacterial S-layer contains a single glycoprotein with an M. of 200 kDa and a carbohydrate content of about 10% by weight. Since procaryotes lack all the organelles engaged in eucaryotic glycoprotein biosynthesis, this discovery has stimulated further work on the structure and biosynthesis of this glycoprotein (for a review, see Sumper 1987; Lechner and Wieland, 1989). The halobacterial S-layer is very tightly joined to the plasma membrane as these cells lack a rigid sacculus as well as an outer membrane. S-layer proteins represent the outermost component of the cell envelope and, as a consequence, these proteins are in immediate contact with the environment. Therefore they are considered ideal model systems to study the adaptation of protein structures to unfavourable conditions. The extreme habitat of halobacteria imposes particularly serious problems with respect to the stabilization of the protein structure. Since other members of the halobacterial family only tolerate moderately halophilic conditions (e.g., Haloferax volcanii requires 2.3M NaC1 for optimum growth), a comparison of the corresponding S-layer protein structures should give hints on how adaptation to high salt conditions works.
15 citations