g(m1)-ganglioside and Down-Syndrome

The earliest event so far known that occurs in the brain affected with Alzheimer's disease (AD) is the deposition and fibril formation of amyloid beta-protein (A beta). A beta is cleaved from a glycosylated membrane protein, called beta-amyloid protein precursor, and normally secreted into the extracellular space. Here we report on the presence of membrane-bound A beta that tightly binds GM1 ganglioside. This suggests that this novel A beta species, rather than secreted A beta, may act as a 'seed' for amyloid and further that intracellular abnormalities in the membrane recycling already exist at the stage of amyloidogenesis.

Topics: Adult; Aging; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Cerebral Cortex; Down Syndrome; G(M1) Ganglioside; Humans; Membrane Glycoproteins; Middle Aged; Neurofibrillary Tangles; Peptide Fragments