Chediak-Higashi syndrome (CHS) in humans and a related murine syndrome(beige) are characterized by albinism, coagulopathy and recurrent infections. The disorders are associated with mutations in LYST — one of a family of proteins possessing a common BEACH domain and a series of C-terminal WD motifs. LYST is thought to play a role in lysosome function, but little is known about the function(s) of other BEACH-family proteins. Pierre Cosson and co-workers have therefore investigated the roles of two BEACH-family proteins(LvsA and LvsB) present in the model organism Dictyostelium. They show that the lvsA mutant secretes lysosomal enzymes normally but exhibits defective localization of the early endosomal marker vacuolar H+-ATPase and reduced phagocytosis. The novel lvsB mutant by contrast exhibits increased lysosomal secretion and only marginally reduced phagocytosis. These findings implicate the two proteins in control of different stages of the endocytic pathway. LvsB might act as a negative...

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