Betaine-homocysteine methyltransferase is a developmentally regulated enzyme crystallin in rhesus monkey lens

P. Vasantha Rao, Timothy A. Garrow, Faith John, Donita Garland, Norman S. Millian, J. Samuel Zigler

Research output: Contribution to journalArticle

Abstract

We describe herein the characterization of a major 45-kDa protein from the soluble βH-crystallin fraction of rhesus monkey (Macaca mulatta) lens. Based on partial peptide sequence, immunoreactivity, and enzymatic activity, this protein has been identified as betaine-homocysteine S-methyltransferase (BHMT: EC 2.1.1.5), an enzyme that catalyzes the methylation of homocysteine using either betaine or thetins as methyl donors. This protein was found to be expressed abundantly in the nuclear region of the monkey lens, reaching 10% of the total nuclear protein, but was barely detectable in the epithelium and cortex regions of the lens. Because the nucleus represents the early embryonic and fetal stages of lens development, we infer that BHMT expression in the lens of the eye is developmentally regulated. By virtue of its high abundance, BHMT can be considered an enzyme crystallin (ψ-crystallin). This is the first enzyme crystallin to be found in primate lenses.

Original languageEnglish (US)
Pages (from-to)30669-30674
Number of pages6
JournalJournal of Biological Chemistry
Volume273
Issue number46
DOIs
StatePublished - Nov 13 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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