Group VIII - Simple Type 1 Receptors
The simple type 1 receptor group of CTLD-containing cell surface proteins has two members in both human and mouse. In simple type 1 receptors, a single CTLD is separated from the transmembrane domain by a short neck region. The cytoplasmic tail contains potential internalization motifs.
Layilin is a widely-expressed protein localized to the membrane ruffles of migrating and spreading cells. The CTLD in layilin binds hyaluronan in the matrix, while the cytoplasmic tail interacts with soluble proteins of the talin family, which in turn bind to the actin cytoskeleton. Therefore, layilin may have a role in cell-matrix adhesion, the formation of membrane ruffles, and the transmission of signals from the extracellular matrix to the cytoskeleton. Chondrolectin is expressed in muscle and other tissues, but its function is unknown.
The CTLDs in simple type 1 receptors contain some of the residues which are known to be involved in the binding of mannose-type sugars by other CTLDs. The mechanism of hyaluronan binding by layilin is not known and the role of carbohydrate recognition in the function of simple type 1 receptors is not clear.
