The proteome of the developing tooth of the sea urchin, Lytechinus variegatus: Mortalin is a constituent of the developing cell syncytium

Keith Alvares, Saryu N. Dixit, Elizabeth Lux, Joseph Barss, Arthur Veis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Echinoderm teeth are continuously growing calcite-mineralized tissues of complex structure. Two features are of special interest: (1) cell division takes place in a restricted aboral domain, the plumula, and the cells immediately merge into multinucleated syncytial layers; (2) the major part of the heavily mineralized tooth elongates and moves towards the adoral incisal tip continuously as the syncytial cells actively expand the syncytium and intermembrane mineral phase. As the first step to understanding the nature of the mineralization processes, we have isolated the proteins of the plumula and of the mature mineralized portions of the tooth, and begun their characterization. Peptide sequences were used to screen a plumula cDNA library by polymerase chain reaction. One primer set yielded a prominent amplified product which was cloned, and sequenced. Comparison with the nucleotide and protein data banks revealed the protein to be Mortalin, a member of the hsp-70 family, with >75% of its sequences identical to that of human mortalin. Immunocytochemical localization of mortalin within the plumula, using Anti-human Grp75, showed staining of the odontoblast cytosol and matrix at the point where syncytial formation was occurring. The cytosol of the syncytial layers was weakly stained. The nuclei within the syncytia were stained at their periphery. In the mature part of the tooth, the perinuclear staining of the nuclei was more prominent. We conclude that mortalin is involved in syncytium formation and maintenance. The urchin mortalin has a distinctive aspartic acid and serine-rich C-terminal domain that may link it to the mineralization process.

Original languageEnglish (US)
Pages (from-to)357-370
Number of pages14
JournalJournal of Experimental Zoology Part B: Molecular and Developmental Evolution
Issue number4
StatePublished - Jul 15 2007

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Medicine
  • Animal Science and Zoology
  • Genetics
  • Developmental Biology


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