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Characterization of squid enolase mRNA: sequence analysis, tissue distribution, and axonal localization
J T Chun1, A E Gioio, M Crispino
1Department of Psychiatry, University of Pittsburgh School of Medicine, Pennsylvania 15213, USA.
Neurochemical Research
|August 1, 1995
Summary
Researchers identified the primary structure of squid enolase, a crucial glycolytic enzyme. This invertebrate enzyme shows significant sequence identity to vertebrate enolase, particularly the alpha isoform, and is present in the squid giant axon.
Area of Science:
- Biochemistry
- Molecular Biology
- Neuroscience
Background:
- Enolase is a highly conserved glycolytic enzyme.
- Mammalian enolase exists as alpha, beta, and gamma subunits.
- Limited data exists on invertebrate enolase primary structure.
Purpose of the Study:
- To isolate and determine the primary structure of enolase from the squid nervous system.
- To compare squid enolase sequence with vertebrate homologues.
- To investigate the expression of enolase mRNA in different squid tissues and the giant axon.
Main Methods:
- Isolation of overlapping cDNA clones.
- Sequencing of cDNA to determine the composite primary structure.
- Cross-species sequence comparison.
- Northern analysis for mRNA expression.
- In situ hybridization and PCR for localization.
Main Results:
- A 1575 bp composite cDNA sequence for squid enolase was obtained, including the full coding region.
- Squid enolase shares over 70% sequence identity with vertebrate enolases, most similar to human alpha-enolase.
- A single 1.6 kb mRNA species was detected, with a 10-fold difference in abundance across tissues.
- Enolase mRNA was found in the squid giant axon.
Conclusions:
- Squid enolase represents a conserved invertebrate form of the enzyme.
- The structural similarity suggests functional conservation with vertebrate alpha-enolase.
- Enolase expression is regulated and localized within the squid nervous system, including the giant axon.