Cadherin 23-like polypeptide in hair bundle mechanoreceptors of sea anemones

• Published in: Journal of Comparative Physiology Vol. 194; no. 9; pp. 811 - 820
• Main Authors: Watson, Glen M., Pham, Lankhanh, Graugnard, Erin M., Mire, Patricia
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2008; Springer Nature B.V
• Subjects: Animal Physiology; Animals; Antibodies - pharmacology; Biomedical and Life Sciences; Cadherins - chemistry; Cadherins - immunology; Cadherins - metabolism; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cilia - metabolism; Cilia - ultrastructure; Evolution, Molecular; Fluorescent Antibody Technique; Immunohistochemistry; Life Sciences; Marine; Mechanoreceptors - drug effects; Mechanoreceptors - metabolism; Mechanoreceptors - ultrastructure; Mechanotransduction, Cellular - drug effects; Mechanotransduction, Cellular - physiology; Microscopy, Electron, Transmission; Molecular Sequence Data; Nematostella vectensis; Neurosciences; Original Paper; Peptides - chemistry; Peptides - metabolism; Phylogeny; Protein Structure, Tertiary - physiology; Sea Anemones - metabolism; Sea Anemones - ultrastructure; Sensory Receptor Cells - drug effects; Sensory Receptor Cells - metabolism; Sensory Receptor Cells - ultrastructure; Sequence Homology, Amino Acid; Zebrafish Proteins - chemistry; Zebrafish Proteins - immunology; Zebrafish Proteins - metabolism; Zoology; Hair cell; Tip link; Sensory transduction
• ISSN: 0340-7594; 1432-1351
• DOI: 10.1007/s00359-008-0352-0

We investigated hair bundle mechanoreceptors in sea anemones for a homolog of cadherin 23. A candidate sequence was identified from the database for Nematostella vectensis that has a shared lineage with vertebrate cadherin 23s. This cadherin 23-like protein comprises 6,074 residues. It is an integral protein that features three transmembrane alpha-helices and a large extracellular loop with 44 contiguous, cadherin (CAD) domains. In the second half of the polypeptide, the CAD domains occur in a quadruple repeat pattern. Members of the same repeat group (i.e., CAD 18, 22, 26, and so on) share nearly identical amino acid sequences. An affinity-purified antibody was generated to a peptide from the C-terminus of the cadherin 23-like polypeptide. The peptide is expected to lie on the exoplasmic side of the plasma membrane. In LM, the immunolabel produced punctate fluorescence in hair bundles. In TEM, immunogold particles were observed medially and distally on stereocilia of hair bundles. Dilute solutions of the antibody disrupted vibration sensitivity in anemones. We conclude that the cadherin 23-like polypeptide likely contributes to the mechanotransduction apparatus of hair bundle mechanoreceptors of anemones.