Biomedical subjects

I Lundell

Publications and source records attributed to I Lundell.

22 records · Page 2Linked to original sources

PubMed1993

Evolutionary conservation of synaptosome-associated protein 25 kDa (SNAP-25) shown by Drosophila and Torpedo cDNA clones.

The neuron-specific proteins SNAP-25 (synaptosome-associated protein 25 kDa), synaptobrevin and syntaxin, are localized to presynaptic terminals in mammals and have been found to associate with proteins involved in vesicle docking and membrane fusion. We describe here SNAP-25 cDNA clones from the fruit fly Drosophila melanogaster and the ray Torpedo marmorata. In situ hybridization showed that SNAP-25 mRNA is exclusively found in brain and ganglia in Drosophila with a pattern suggesting expression in most neurons. The Drosophila and Torpedo proteins show 61 and 81% amino acid identity to mouse SNAP-25, a degree of conservation similar to that previously reported for synaptobrevin. None of the SNAP-25 sequences has a membrane-spanning region, but all contain a cluster of cysteine residues that can be palmitoylated for membrane attachment. SNAP-25 displays sequence similarity to syntaxin A and B. These data show that SNAP-25 and synaptobrevin, which are both implicated in vesicle docking and/or membrane fusion, have both been highly conserved during evolution. This supports the existence of a basic molecular machinery for synaptic vesicle docking in vertebrate and invertebrate synapses.

Amino Acid Sequence↗

PubMed1993

Molecular cloning of a functional human thyrotropin-releasing hormone receptor.

A cDNA encoding the human thyrotropin-releasing hormone receptor (hTRH-R) was isolated from a human brain cDNA library. Screening of 1.2 million clones resulted in 2 candidates. The largest clone contained TRH-R homologous sequences starting in the third transmembrane domain and included a long 3' untranslated sequence. The smaller clone contained a potential start of the open reading frame, but was interrupted by an intron in the sixth transmembrane domain. The two clones had 497 bp of overlapping identical sequences and it was possible to assemble a complete cDNA thus restoring the assumed coding sequence. Electrophysiological studies of frog oocytes injected with in vitro transcribed mRNA showed TRH-specific inward currents, demonstrating that the reconstituted cDNA encoded a functional receptor. The predicted amino acid sequence of the hTRH-R protein showed high homology with the rat and mouse TRH-Rs with the exception of their C-terminal region. The human TRH-R gene seems to contain two introns.

Amino Acid Sequence↗

PubMed1992

Strong evolutionary conservation of neuropeptide Y: sequences of chicken, goldfish, and Torpedo marmorata DNA clones.

Neuropeptide Y (NPY) is an abundant and widespread neuropeptide in the nervous system of mammals. NPY belongs to a family of 36-amino acid peptides that also includes pancreatic polypeptide and the endocrine gut peptide YY as well as the fish pancreatic peptide Y. To study the evolution of this peptide family, we have isolated clones encoding NPY from central nervous system cDNA libraries of chicken, goldfish, and the ray Torpedo marmorata, as well as from a chicken genomic library. The predicted chicken NPY amino acid sequence differs from that of rat at only one position. The goldfish sequence differs at five positions and shows that bony fishes have a true NPY peptide in addition to their pancreatic peptide Y. The Torpedo sequence differs from that of rat at three positions. As Torpedo NPY has no unique positions when compared with the other sequences, it seems to be identical to the NPY of the common ancestor of cartilaginous fishes, bony fishes, and tetrapods after 420 million years of evolution. The 30-amino acid carboxyl-terminal extension of the NPY precursor also displays considerable sequence conservation. These results show that NPY is one of the most highly conserved neuroendocrine peptides.

Amino Acid Sequence↗

PubMedDate not supplied

Binding of chimeric NPY/galanin peptides M32 and M242 to cloned neuropeptide Y receptor subtypes Y1, Y2, Y4, and Y5.

Ligand binding to neuropeptide Y (NPY) receptors Y1, Y2, Y4, and Y5 from guinea-pig was investigated using the two NPY-galanin hybrids M32 (galanin1-13-NPY25-36-amide) and M242 ([D-Trp(32)]M32). The affinity of M32 for Y1, Y2, and Y4 receptors was 13, 4, and 30nM, respectively, similar to that of NPY18-36 and NPY22-36 but 40-fold to 300-fold lower than the affinity of intact porcine NPY. M242 bound to the Y1, Y2, and Y4 receptors with 9-fold to 20-fold lower affinity than did M32. The affinities of M32 and M242 for Y5 were 400 and 800 nM, respectively. Thus, M32 seems to gain affinity relative to both of its constituent peptide portions although the NPY25-36 part may be sufficient for NPY-receptor recognition, especially at the Y2 receptor. This suggests that the galanin portion of M32 influences and/or stabilizes the conformation of the NPY portion, similar to the effect seen for the NPY portion of M32 in binding to galanin receptors.

Amino Acid Sequence↗