|
KMID : 0613820120220010098
|
|
Journal of Life Science
2012 Volume.22 No. 1 p.98 ~ p.109
|
|
|
Lactate Dehydrogenase and Monocarboxylate Transporters 1, 2, and 4 in Tissues of Micropterus salmoides
|
|
Yum Jung-Joo
Yeon Jun-Hee
|
|
|
Abstract
|
|
|
|
The properties of lactate dehydrogenase (EC 1.1.1.27, LDH) and expression of monocarboxylate transporters (MCTs) 1, 2, and 4 were studied in tissues from Micropterus salmoides. Native-PAGE revealed that the LDH A₄ isozyme was predominantly located in skeletal muscle. The LDH A₄, A₂B₂, and B₄ isozymes were detected in heart, liver, eye, and brain tissues, while eye-specific C₄ isozyme was detected in eye tissue. In September, strong LDH B₄ isozyme activity was detected in heart tissue. High A₄ isozyme activity was noted in all other tissues except heart tissue. However, in November, strong A₄ isozyme activity was detected in heart tissue. The LDH/CS (Citrate synthase, EC 4.1.3.7) ratio in skeletal muscle and heart tissues indicated that anaerobic metabolism was high in those tissues. Native-PAGE after immunoprecipitation showed that eye-specific C₄ isozyme was more similar to the A₄ than the B₄ isozyme. The LDH A₄ isozyme was purified by affinity chromatography. The molecular weight of subunit A was 37,200. The LDH activity in tissues was consistently 11.05~28.32% due to inhibition by 10 mM pyruvate. The K_m^{PYR} of LDH in eye tissue was very low. The optimum pH for LDH in tissues was pH 7.5~8.0. The LDH A₄ isozyme was detected in mitochondria of skeletal muscle, whereas the B₄ and A₂B₂ isozymes were detected in heart tissue mitochondria. Western blot analysis indicated that MCTs 1, 2, and 4 were located in the plasma membrane and mitochondria of skeletal muscle and heart tissues. The sizes of MCTs 1, 2, and 4 in skeletal muscle were 60, 54~38, and 63 kDa, while those in heart tissue were 57, 54~38, and 55.5 kDa, respectively. In conclusion, M. salmoides appears to use anaerobic metabolism predominantly when adapted to a hypoxic environment. In highly activated skeletal muscle and heart tissue, energy production is controlled by inward and outward flows of pyruvate and lactate through MCTs 1, 2, and 4 in the plasma membrane and mitochondria, with effective adjustment by LDH isozymes.
|
|
|
KEYWORD
|
|
|
Largemouth bass (Micropterus salmoides), lactate dehydrogenase (LDH), K_m^{PYR}, monocarboxylate transporters (MCT) 1, 2, 4
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|