Localisation of neurone-specific enolase (ENO2) to 12p13

We have localised the human cDNA for neurone-specific enolase (ENO2) to chromosome region 12p13 by in situ hybridisation. Two additional smaller peaks of hybridisation to specific chromosomal subregions were observed. That on chromosome 1p36 probably represents cross-hybridisation to the locus for nonneuronal enolase (ENO1), which has been previously localised to this chromosome and with which ENO2 shares homology. A further gene for a member of the enolase family may be responsible for the hybridisation to chromosome 17.

Complete amino acid sequence of the neurone-specific gamma isozyme of enolase (NSE) from human brain and comparison with the non-neuronal alpha form (NNE)

The complete amino acid sequence (433 residues) of the human neurone-specific gamma isozyme of enolase (NSE) has been determined by a combination of direct amino acid sequencing and nucleotide sequencing of cloned cDNA. Substantial amino acid sequence of the non-neuronal alpha form of the enzyme was also obtained which agreed almost entirely with the indirect cDNA sequence. Comparison of the two human sequences shows no insertions or deletions, but 72 replacements. Comparison of the human gamma form with the corresponding isozyme from the rat shows only 7 replacements (compared to 27 changes between the human and rat alpha isozymes). We have identified regions of sequence difference between the human alpha and gamma forms that are mainly hydrophilic in character (residues 271-285, 298-316 and 416-433). These residues are on the surface of the three-dimensional structure and could be useful as immunogens to produce antibodies specific for the neurone-specific form.

The diffuse neuroendocrine system: a molecular perspective

This review seeks to illustrate that the concept of a 'diffuse neuroendocrine system' arises from a series of ontogenetic, phylogenetic and functional overlaps borne out at the molecular level, which engender an apparent global unit. Extrapolation from the overlaps should lead to the discovery of new facets in the relationships between molecular components of the DNES, and this approach will lead to a spectrum of markers and probes with a variety of clinical applications. Initial approaches progressed from cellular function toward molecular anatomy, but converse questions starting from anatomical markers are now arising.

Sequence conservation in the 3'-untranslated regions of neurone-specific enolase, lymphokine and protooncogene mRNAs

The C-terminal protein-coding and the entire 3'-untranslated regions of a cDNA corresponding to human neurone-specific enolase mRNA have been sequenced. The 3'-untranslated region is 892 bases long and shows a high degree of homology with the 3'-untranslated region of rat neurone-specific enolase mRNA. This sequence conservation is not seen in non-neuronal enolase mRNAs. Features of the conserved sequence include an A-rich region approx. 250 bases from the stop codon at a point corresponding to the polyadenylation signal site in non-neuronal enolase mRNA, and a repeating ATTT sequence. This unusual motif in eukaryotic mRNAs has previously been reported in the 3'-untranslated regions of lymphokine and protooncogene mRNAs.

Molecular cloning of cDNA coding for human PGP 9.5 protein. A novel cytoplasmic marker for neurones and neuroendocrine cells

The co-ordinate sequencing of the human neuronal and neuroendocrine marker protein PGP 9.5 and its cDNA is described. The cDNA encodes the complete protein (212 amino acids), and the 340 nucleotide 3'-noncoding region including the polyadenylation signal, indicating an mRNA slightly larger than 1 kb in size. Protein sequencing of 50% of PGP 9.5 confirms the deduced protein sequence.

Levels of immunoreactive aldolase C, creatine kinase-BB, neuronal and non-neuronal enolase, and 14-3-3 protein in circulating human blood cells

Five proteins found in the human nervous system have been measured by radioimmunoassay in human red cells, platelets, and lymphocytes. Two neuronal proteins (neurone-specific enolase and 14-3-3 protein) occur in platelets at levels equivalent to their concentration in brain, and in erythrocytes at levels approximately 10% of the level in brain. Two proteins characteristic of astrocytes in the cerebral cortex (creatine kinase BB and aldolase C) occur at low levels in platelets and are virtually undetectable in erythrocytes and lymphocytes. The more widely distributed non-neuronal enolase is present in erythrocytes, platelets and lymphocytes. The neurone-specific enolase and 14-3-3 protein immunoreactivities found in circulating blood cells have been characterised in terms of molecular mass, charge, and dilution characteristics in the respective radioimmunoassay and in each case appears to represent the intact protein. Controlled lysis of erythrocytes releases neurone-specific enolase and 14-3-3 protein in parallel with haemoglobin. The occurrence of brain proteins in circulating blood cells (which appears to be a species-dependent phenomenon) has the practical clinical consequence that minor degrees of especially red cell lysis can produce high serum levels of immunoreactivity. This represents a pitfall in the measurement of these proteins in serum as tumour markers or as indices of damage to the central nervous system.