Extracellular calcium stimulates Na+-dependent putrescine uptake in B16 melanoma cells

Minchin, RF and Martin, RL (1997) Extracellular calcium stimulates Na+-dependent putrescine uptake in B16 melanoma cells. International Journal of Biochemistry & Cell Biology, 29 3: 447-454. doi:10.1016/S1357-2725(96)00145-8


Author Minchin, RF
Martin, RL
Title Extracellular calcium stimulates Na+-dependent putrescine uptake in B16 melanoma cells
Journal name International Journal of Biochemistry & Cell Biology   Check publisher's open access policy
ISSN 1357-2725
Publication date 1997-01-01
Sub-type Article (original research)
DOI 10.1016/S1357-2725(96)00145-8
Volume 29
Issue 3
Start page 447
End page 454
Total pages 8
Language eng
Abstract The regulation of putrescine transport in difluoromethylornithine-treated B16 melanoma cells by extracellular Ca2+ has been investigated. It was found that physiological concentrations of Ca2+ were essential for optimum uptake of putrescine and spermidine. Mg2+, albeit at higher concentrations, also could potentiate polyamine transport. The maximum rate of putrescine uptake increased from 1698 +/-: 67 pmol/min/mg DNA in the absence of Ca2+ to 3100 +/- 98 pmol/min/mg DNA in the presence of 0.5 mM Ca2+. There was no change in K-m. While Ca2+ enhanced transport of both putrescine and spermidine it did not affect the uptake of deoxyglucose, thymidine or leucine. Putrescine did not alter Ca2+ fluxes suggesting that the two cations do not share a common transport system. The effects of Ca2+ on putrescine uptake appeared to be mediated extracellularly firstly because Ca2+ did not potentiate putrescine uptake in the presence of A23187 and secondly, because the effects of Ca2+ were completely inhibited by the lanthanide Tb3+, which binds to calcium-dependent proteins and does not readily cross biological membranes. Ca2+ did not affect putrescine transport in the absence of extracellular Na+. Moreover, the rate of putrescine uptake in the absence of Ca2+ was similar to that in the absence of extracellular Na+. The results from this study indicate that polyamine transport is stimulated by extracellular Ca2+ and suggest that Ca2+ is required for activity of the Na+-dependent transporter only. This transporter appears to possess a regulatory binding site for divalent cations. (C) 1997 Elsevier Science Ltd.
Keyword Biochemistry & Molecular Biology
Cell Biology
Putrescine
Polyamines
Transport
Calcium
B16 Cells
Polyamine Transport
Spermidine-transport
Feedback Repression
Hepatocytes
Calmodulin
Systems
Acids
Line
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biomedical Sciences Publications
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 2 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 1 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Tue, 14 Aug 2007, 02:51:11 EST