Amino acids and proteins of tectorial membrane (TM)

Abstract

The primary function of the TM is apparently mechanical; nevertheless, certain alterations in its chemical environment exert profound effects upon the shape of the TM, most likely through conformational changes in its fibrous proteins. Thus, elucidation of the chemical nature of the TM is of considerable functional importance. Using two‐dimensional polyacrylamide gel electrophoresis, we have found that the three prominent, high molecular weight proteins (135–155 kDalton) demonstrated by a one‐dimensional technique in the mouse TM [K.P. Steel, Acta Otolaryngol. 89, 27–32 (1980)], are also present in the guinea pig TM. We further found that these three proteins are highly alkaline (pI 8.4–8.6). The free amino acid profile of the TM is remarkably similar to that of endolymph, which supports the concept that the TM is chemically “transparent.” Our data on the amino acid composition of the proteins of the TM, as reflected by analysis of hydrolysates, are in part at variance with earlier studies [S. Iurato, Z. Zellforsch. 52, 105–128 (1960)]; most notably, we found glycine to be significantly higher and hydroxyproline to be present. The potential functional significance of these findings will be discussed. [Work supported by NIH and NSF.]