The Sea Urchin Sperm Receptor for Egg Jelly Is a Modular Protein with Extensive Homology to the Human Polycystic Kidney Disease Protein, PKD1

• Published in: The Journal of cell biology Vol. 133; no. 4; pp. 809 - 817
• Main Authors: Moy, G. W., Mendoza, L. M., Schulz, J. R., Swanson, W. J., Glabe, C. G., Vacquier, V. D.
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 01.05.1996; The Rockefeller University Press
• Subjects: Acrosome reaction; Amino Acid Sequence; Animals; Antibodies; Autosomal dominant polycystic kidney; Base Sequence; Carbohydrate Metabolism; Cell Membrane - metabolism; Cell membranes; Cellular biology; Cloning, Molecular; Eggs; Female; Humans; Ion Channels - metabolism; Kidneys; Male; Marine; Membranes; Molecular Sequence Data; Oligoribonucleotides; Open reading frames; Ova; Ovum - metabolism; Polycystic kidney diseases; Polycystic Kidney, Autosomal Dominant - metabolism; Proteins; Proteins - chemistry; Receptors; Receptors, Cell Surface - chemistry; Receptors, Cell Surface - metabolism; Sea Urchins; Sequence Homology, Amino Acid; Sperm-Ovum Interactions; Spermatozoa; Spermatozoa - metabolism; Strongylocentrotus purpuratus; TRPP Cation Channels
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.133.4.809

During fertilization, the sea urchin sperm acrosome reaction (AR), an ion channel-regulated event, is triggered by glycoproteins in egg jelly (EJ). A 210-kD sperm membrane glycoprotein is the receptor for EJ (REJ). This conclusion is based on the following data: purified REJ binds species specifically to EJ dotted onto nitrocellulose, an mAb to REJ induces the sperm AR, antibody induction is blocked by purified REJ, and purified REJ absorbs the AR-inducing activity of EJ. Overlapping fragments of REJ cDNA were cloned (total length, 5,596 bp). The sequence was confirmed by microsequencing six peptides of mature REJ and by Western blotting with antibody to a synthetic peptide designed from the sequence. Complete deglycosylation of REJ followed by Western blotting yielded a size estimate in agreement with that of the mature amino acid sequence. REJ is modular in design; it contains one EGF module and two C-type lectin carbohydrate-recognition modules. Most importantly, it contains a novel module, herein named the REJ module (700 residues), which shares extensive homology with the human polycystic kidney disease protein (PKD1). Mutations in PKD1 cause autosomal dominant polycystic kidney disease, one of the most frequent genetic diseases of humans. The lesion in cellular physiology resulting from mutations in the PKD1 protein remains unknown. The homology between REJ modules of the sea urchin REJ and human PKD1 suggests that PKD1 could be involved in ionic regulation.