Quantitative carbohydrate analyses of the tectorial and otoconial membranes of the guinea pig.

Carbohydrate composition of the tectorial membrane (TM) and the otoconial membrane (OM) of the guinea pig was analyzed after hydrolysis, using high-performance anion-exchange chromatography and pulsed amperometric detection. Both of the tissues were highly glycosylated; the carbohydrate content being 24-42% of protein. GlcN, Gal, Glc and Man were found to be the major component sugars of TM, whereas little GalN was found. Fuc and NANA were also present, but NGNA was not detectable. After digestion with thermolysin for solubilization, OM was separated into two fractions: insoluble mineral particles of the otoconia (OM-ppt) and a soluble fraction from the gelatinous layer (OM-sup). These two fractions showed distinct carbohydrate composition from each other. Further analyses using glycosidases revealed that TM contained asialyl and monosialyl but little di-, tri- and tetrasialyl N-glycosides, and OM-sup did not seem to be susceptible to endo-beta-galactosidase, which is known to cleave some N-acetyl-polylactosamine and keratan sulfate. Based on these analyses, it can be suggested that most of the carbohydrates in TM are likely to be asialyl and monosialyl N-glycosides. N-Glycosides may be predominant in the otoconia as well, and a polymer structure consisting of GlcN(Ac) and Gal other than N-acetyl-polylactosamine may exist in the gelatinous layer of OM. O-Glycosylation of the usual type appeared to be minor in all the fractions.