Differences in the composition of adhesive and non-adhesive mucus from the limpet Lottia limatula

The mucus used by the limpet Lottia limatula to form glue-like attachments was compared biochemically to the slippery mucus produced during other activities, such as suction adhesion. Colorimetric assays revealed the protein content of the adhesive mucus to be 2.1 times greater than that of the non-adhesive form, and the carbohydrate content to be 1.9 times greater. Both forms of mucus contained roughly six times as much protein as carbohydrate, and there was no difference in their inorganic elemental compositions. Quantitative analysis of the protein content by SDS-PAGE and a scanning densitometer revealed a similar protein composition in both forms of mucus; but three notable differences emerged. First, the overall difference in protein concentration was confirmed. In addition, there was a 118 kD protein that was common only in the adhesive mucus, and a 68 kD protein that occurred only in the non-adhesive mucus.