Lysosomal high molecular weight multienzyme complex

Three acidic glycosidases: beta-galactosidase (beta-GAL, EC 3.2.1.23), alpha-neuraminidase (NEUR, sialidase, EC 3.2.1.18), N-acetylaminogalacto-6-sulfate sulfatase (GALNS, EC 3.1.6.4) and serine carboxypepidase cathepsin A (EC 3.4.16.1) form a functional high molecular weight complex in the lysosomes. The major constituent of this complex is cathepsin A, the so-called "lysosomal protective protein" (PPCA). By forming a multienzyme complex, it protects the glycosidases from rapid intralysosomal proteolysis, and it is also required for the intracellular sorting and proteolytic processing of their precursors. In man, a deficiency of cathepsin A leads to a combined deficiency of beta-GAL and NEUR activities, called "galactosialidosis". Multiple mutations identified in the cathepsin A gene are the molecular basis of this lysosomal storage disease. This review describes the structural organization of the lysosomal high molecular weight multienzyme complex and the importance of the protective protein/cathepsin A in physiology and pathology.

Lichens of the Knyszyńska Forest (NE Poland)

During the period 1991-1999 the lichen species composition of 26 reserves of the Knyszyńska Forest were examined. 315 taxa, including 271 species were found. Epiphytic lichens were predominant, while epilithic species were the least common. Of the coniferous trees, pine (Pinus sylvestis) was the habitat which supported most species (67), and common larch (Larix decidua) the fewest (5). Only two species were found on juniper (Juniper communis). Of deciduous trees, the largest number of species developed on oak bark (Quercus robur) (102), the fewest on elm bark (Ulmus laevis) (2). In the case of deciduous bushes most lichen taxa were noted on hazel (Corylus avellana) (21) and only one on hawthorn (Crataegus monogyna). The commonest species were Hypogymnia physodes and Lecanora conizaeoides, which were encountered in all 26 reserves.