PubMed Health⌕ Search

Biomedical subjects

N Calakos

Publications and source records attributed to N Calakos.

4 recordsLinked to original sources
PubMed1992

Syntaxin: a synaptic protein implicated in docking of synaptic vesicles at presynaptic active zones.

Synaptic vesicles store neurotransmitters that are released during calcium-regulated exocytosis. The specificity of neurotransmitter release requires the localization of both synaptic vesicles and calcium channels to the presynaptic active zone. Two 35-kilodalton proteins (p35 or syntaxins) were identified that interact with the synaptic vesicle protein p65 (synaptotagmin). The p35 proteins are expressed only in the nervous system, are 84 percent identical, include carboxyl-terminal membrane anchors, and are concentrated on the plasma membrane at synaptic sites. An antibody to p35 immunoprecipitated solubilized N-type calcium channels. The p35 proteins may function in docking synaptic vesicles near calcium channels at presynaptic active zones.

Amino Acid Sequence↗
PubMed1992

Synaptic vesicle membrane proteins interact to form a multimeric complex.

Potential interactions between membrane components of rat brain synaptic vesicles were analyzed by detergent solubilization followed by size fractionation or immunoprecipitation. The behavior of six synaptic vesicle membrane proteins as well as a plasma membrane protein was monitored by Western blotting. Solubilization of synaptic vesicle membranes in CHAPS resulted in the recovery of a large protein complex that included SV2, p65, p38, vesicle-associated membrane protein, and the vacuolar proton pump. Solubilization in octylglucoside resulted in the preservation of interactions between SV2, p38, and rab3A, while solubilization of synaptic vesicles with Triton X-100 resulted in two predominant interactions, one involving p65 and SV2, and the other involving p38 and vesicle-associated membrane protein. The multicomponent complex preserved with CHAPS solubilization was partially reconstituted following octylglucoside solubilization and subsequent dialysis against CHAPS. Reduction of the CHAPS concentration by gel filtration chromatography resulted in increased recovery of the multicomponent complex. Examination of the large complex isolated from CHAPS-solubilized vesicles by negative stain EM revealed structures with multiple globular domains, some of which were specifically labeled with gold-conjugated antibodies directed against p65 and SV2. The protein interactions defined in this report are likely to underlie aspects of neurotransmitter secretion, membrane traffic, and the spatial organization of vesicles within the nerve terminal.

Animals↗
PubMed1989

Does compliance mismatch alone cause neointimal hyperplasia?

To define the relationship between compliance mismatch and the development of neointimal hyperplasia, one 3 cm segment of common iliac artery was externally banded in seven dogs, thereby fixing the arterial diameter at end diastole. To quantify compliance, end-diastole diameter and its change with pulse pressure were measured by induction angiometry. This technique uses intravascular soft trifilar wire probes introduced through distally placed polytetrafluoroethylene sidearms. Compliance was checked in the banded and contralateral undissected unbanded control iliac arteries at 3 and 6 months, at which times the vessels were fixed by perfusion, excised, and examined histologically. Sustained (6-month) compliance mismatch was successfully induced within the banded segments (p less than 0.0001), and no compliance mismatch was seen in the control segments (p = 0.357). The intima of all banded vessels was virtually indistinguishable from that in controls grossly and histologically. Mild focal intimal thickening, less than 3 cell layers thick involving less than 5% of the vessel circumference, was typically seen in both banded and control vessels (range 6.57 +/- 6.80 micron to 38.86 +/- 57.16 micron). In marked contrast, at the sites of the polytetrafluoroethylene-to-femoral artery anastomosis, near-occlusive neointimal hyperplasia (1714 +/- 415.47 micron) was seen in all animals. Residual lumen area in the banded and control vessels was only minimally abnormal (range 98.65% +/- 2.18% to 99.96% +/- 0.08%). These data indicate that compliance mismatch alone is an insufficient stimulus for the development of neointimal hyperplasia in the canine model.

Animals↗