TY - JOUR
T1 - Sodium-dependent carnitine transport in human placental choriocarcinoma cells
AU - Prasad, Puttur D
AU - Huang, Wei
AU - Ramamoorthy, Sammanda
AU - Carter, A. Lee
AU - Leibach, Frederick H.
AU - Ganapathy, Vadivel
N1 - Funding Information:
This work was supported by National Institutes of Health Grant HD 24451. The authors thank Sarah A. Taylor for expert secretarial assistance.
PY - 1996/10/2
Y1 - 1996/10/2
N2 - The JAR human placental choriocarcinoma cells were found to transport carnitine into the intracellular space by a Na+-dependent process. The transport showed no requirement for anions. The Na+-dependent process was saturable and the apparent Michaelis-Menten constant for carnitine was 12.3 ± 0.5 μM Na+ activated the transport by increasing the affinity of the transport system for carnitine. The transport system specifically interacted with L-carnitine, D-carnitine, acetyl-DL-carnitine and betaine. 6-N-Trimethyllysine and choline had little or no effect on carnitine transport. Of the total transport measured, transport into the intracellular space represented 90%. Plasma membrane vesicles prepared from JAR cells were found to bind camitine in a Na+-dependent manner. The binding was saturable with an apparent dissociation constant of 0.66 ± 0.08 μM. The binding process was specific for L-carnitine, D-carnitine, acetyl-DL-carnitine, and betaine. 6-N-Trimethyllysine and choline showed little or no affinity. It is concluded that the JAR cells express a Na+-dependent high-affinity system for carnitine transport and that the Na+-dependent high-affinity carnitine binding detected in purified JAR cell plasma membrane vesicles is possibly related to the transmembrane transport process.
AB - The JAR human placental choriocarcinoma cells were found to transport carnitine into the intracellular space by a Na+-dependent process. The transport showed no requirement for anions. The Na+-dependent process was saturable and the apparent Michaelis-Menten constant for carnitine was 12.3 ± 0.5 μM Na+ activated the transport by increasing the affinity of the transport system for carnitine. The transport system specifically interacted with L-carnitine, D-carnitine, acetyl-DL-carnitine and betaine. 6-N-Trimethyllysine and choline had little or no effect on carnitine transport. Of the total transport measured, transport into the intracellular space represented 90%. Plasma membrane vesicles prepared from JAR cells were found to bind camitine in a Na+-dependent manner. The binding was saturable with an apparent dissociation constant of 0.66 ± 0.08 μM. The binding process was specific for L-carnitine, D-carnitine, acetyl-DL-carnitine, and betaine. 6-N-Trimethyllysine and choline showed little or no affinity. It is concluded that the JAR cells express a Na+-dependent high-affinity system for carnitine transport and that the Na+-dependent high-affinity carnitine binding detected in purified JAR cell plasma membrane vesicles is possibly related to the transmembrane transport process.
KW - Carnitine
KW - High-affinity binding
KW - High-affinity transport
KW - Human placenta
KW - JAR choriocarcinoma cell
KW - Plasma membrane
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U2 - 10.1016/0005-2736(96)00126-5
DO - 10.1016/0005-2736(96)00126-5
M3 - Article
C2 - 8865821
AN - SCOPUS:0030566162
SN - 0005-2736
VL - 1284
SP - 109
EP - 117
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 1
ER -