Biochemical Characterization of Tektins from Sperm Flagellar Doublet Microtubules

• Published in: The Journal of cell biology Vol. 104; no. 4; pp. 1069 - 1075
• Main Authors: Linck, R. W., Stephens, R. E.
• Format: Journal Article
• Language: English
• Published: New York, NY Rockefeller University Press 01.04.1987; The Rockefeller University Press
• Subjects: Amino acids; Amino Acids - analysis; Animals; Biochemistry; Biological and medical sciences; Cell structures and functions; Cells; Chemical composition; Chromatography, High Pressure Liquid; Coincidence; Cytoskeleton, cytoplasm. Intracellular movements; Elution; flagella; Flagella - ultrastructure; Fundamental and applied biological sciences. Psychology; Gels; Male; Microtubule Proteins - isolation & purification; Microtubules; Microtubules - ultrastructure; Molecular and cellular biology; Molecular Weight; Peptide Mapping; Sea Urchins; Solvents; Spermatozoa; Spermatozoa - ultrastructure; Strongylocentrotus purpuratus; tektins; Trypsin; Tubulin - isolation & purification; Spermatozoa; Purification; Molecular structure; Echinodermata; Flagellum; Tektin; Characterization; Proteins; Polypeptide; Echinoidea; Microtubule; Invertebrata; Sea urchin
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.104.4.1069

Tektins, protein components of stable protofilaments from sea urchin sperm flagellar outer doublet microtubules (Linck, R. W., and G. L. Langevin, 1982, J. Cell Sci., 58:1-22), are separable by preparative SDS PAGE into 47-, 51-, and 55-kD equimolar components. High resolution two-dimensional tryptic peptide mapping reveals 63-67% coincidence among peptides of the 51-kD tektin chain and its 47- and 55-kD counterparts, >70% coincidence between the 47- and 55-kD tektins, but little obvious similarity to either α- or β-tubulin. With reverse-phase HPLC on a C18column, using 6 M guanidine-HCl solubilization and a 0.1% trifluoroacetic acid/ CH3CN gradient system (Stephens, R. E., 1984, J. Cell Biol. 90:37a [Abstr.]), the relatively less hydrophobic 51-kD tektin elutes at >45% CH3CN, immediately followed by the 55-kD chain. The 47-kD tektin is substantially more hydrophobic, eluting between the two tubulins. The amino acid compositions of the tektins are very similar to each other but totally distinct from tubulin chains, being characterized by a >50% higher arginine plus lysine content (in good agreement with the number of tryptic peptides) and about half the content of glycine, histidine, proline, and tyrosine. The proline content correlates well with the fact that tektin filaments have twice as much α-helical content as tubulin. Total hydrophobic amino acid content correlates with HPLC elution times for the tektins but not tubulins. The average amino acid composition of the tektins indicates that they resemble intermediate filament proteins, as originally postulated from structural, solubility, and electrophoretic properties. Tektins have higher cysteine and tryptophan contents than desmin and vimentin, which characteristically have only one residue of each, more closely resembling certain keratins in these amino acids.