Acetylcholinesterase and Butyrylcholinesterase Expression in Adult Rabbit Tissues and During Development

Authors


  • Note. The novel nucleotide sequence data published here has been deposited with the Genbank sequence data bank and is available under accession numbers U 05036 (rabbit AChE) and X52090-X52092 (rabbit BChE).

A. Chatonnet, Différenciation cellulaire et Croissance, Centre INRA de Montpellier, 2 place Viala, F-34060 Montpellier Cedex 1, France
Fax: +33 67 54 56 94.

Abstract

A large cDNA fragment covering the complete sequence of the mature catalytic subunit of rabbit acetylcholinesterase (AChE) has been cloned and sequenced. This sequence was compared to that of rabbit butyrylcholinesterase [BChE; Jbilo, O. & Chatonnet, A. (1990) Nucleic Acids Res. 18, 3990]. Amino acid sequences of AChE and BChE have 51% identity. They both possessed a choline-binding site W84, a catalytic triad S200-H440-E327 and six cysteine residues (positions 67–94, 254–265, 402–521) in conserved sequence positions to those that form three intrachain disulfide bonds in all cholinesterases (by convention, numbering of amino acids is that used for Torpedo AChE). Rabbit AChE had a larger number of aromatic residues lining the active-site gorge than rabbit BChE (14 compared to 8, respectively) and a smaller number of potential N-glycosylation sites (3 compared to 8, respectively). Both catalytic subunits have a hydrophilic C-terminus (catalytic subunits of type T). Expression of acetycholinesterase and butyrylcholinesterase genes (ACHE and BCHE) was studied in rabbit tissues and during development by a correlation of Northern-blot analysis and enzymic activities. This correlation was rendered difficult by the presence of an eserine-resistant esterase active on butyrylthiocholine in serum, liver and lung. When the contribution of this carboxylesterase was taken into account, brain was found as the richest source of BChE followed by lung and heart. Rabbit liver had a very low content of BChE that correlated with the low BChE activity in plasma. During development, BCHE transcripts were detected as early as day 10 post coitum, whereas ACHE transcripts appeared only on day 12.

Abbreviations
AChE and BChE

acetylcholinesterase and butyrylcholinesterase enzymes

ACHE and BCHE

genes encoding AChE and BChE

Brij 96

10-oleylether

Iso-OMPA

tetramonoisopropylpyrophosphortetramide

LS, LSB, HS and HSB

low salt, low-salt Brij, high salt and high-salt Brij buffers

Enzymes
 

Carboxylesterases (EC 3.1.1.1)

 

acetylcholinesterase (EC 3.1.1.7)

 

butyrylcholinesterase (EC 3.1.1.8)

 

alkaline phosphatase (EC 3.1.3.1)

 

β-galactosidase (EC 3.2.1.23)

Ancillary