Z-protein, a component of the skeletal muscle Z-line, is located at the apical tips of microvilli of chicken intestinal epithelial cells.

Antiserum against Z-protein, which is one of the components of myofibrillar Z-lines, strongly stained the epithelial cells of chicken small intestine at the apical tips of the microvilli and the junctional complexes. Immunoblot tests with anti-Z-protein antiserum showed that there is a peptide of the same antigenicity as myofibrillar Z-protein in the components of the epithelial cells of chicken small intestine. Hence it seems that the apical tip of the microvillus contains a constituent corresponding to the Z-protein of myofibrillar Z-line.