Aquatic Research Cluster, CREAIT Network, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
J Comp Physiol B. 2014 May;184(4):483-96. doi: 10.1007/s00360-014-0810-7. Epub 2014 Feb 20.
GLUTs 1-4 are sodium-independent facilitated glucose transporters and are considered to play a major role in glucose trafficking. The relative transcript levels of GLUTs 1-4 were determined in tissues of Atlantic cod (Gadus morhua). The distribution profile of GLUTs normalized to RNA is similar to mammals and with a few exceptions other fish. GLUT1 is ubiquitous, GLUT2 is relatively abundant in tissues that release glucose, GLUT3 expression is relatively strong in brain, and GLUT4 is relatively high in heart and muscle. The functionally significant level of transcript is presumably the level in the cell. Normalization of relative GLUT levels to tissue mass reveals there are extremely high levels of GLUT1 transcript in gas gland consistent with the high lactate production rates, GLUT3 is dominant in gill and head kidney as well as brain, and GLUT4 expression in gill is elevated relative to other tissues. Consideration of GLUTs within tissues reveals that GLUT1 is the dominant transcript in a group of tissues including gas gland, heart, white muscle, and RBCs. Brain, gill, and spleen display a co-dominance of GLUTs 1 and 3. There are relatively low levels of GLUT4 in most tissues, the highest being found in white muscle where GLUT4 accounts for only 12 % of the total transcript level. The apparent low level of GLUT4 transcript may reflect two tissues that were not included in the current study, red muscle and adipose tissue, due to their low abundance in Atlantic cod. The rate of glucose metabolism in isolated cells prepared from gas gland, heart, and RBCs was determined by tracking the rate of (3)H2O production from [2-(3)H]-glucose. The steady-state rate of basal glycolysis in these three tissues correlates with relative transcript levels of GLUT1.
GLUTs 1-4 是钠离子非依赖性易化葡萄糖转运体,被认为在葡萄糖转运中起主要作用。在大西洋鳕鱼(Gadus morhua)的组织中确定了 GLUTs 1-4 的相对转录水平。GLUTs 的分布谱与哺乳动物相似,RNA 归一化时有几个例外。GLUT1 普遍存在,GLUT2 在释放葡萄糖的组织中相对丰富,GLUT3 在大脑中的表达相对较强,GLUT4 在心脏和肌肉中的含量相对较高。功能上重要的转录水平大概是细胞中的水平。将相对 GLUT 水平与组织质量归一化表明,在与高乳酸生成速率一致的气腺中存在极高水平的 GLUT1 转录本,GLUT3 在鳃和头肾以及大脑中占主导地位,并且在鳃中的 GLUT4 表达相对于其他组织升高。考虑组织内的 GLUTs 表明,GLUT1 是包括气腺、心脏、白肌和 RBC 在内的一组组织中的主要转录本。大脑、鳃和脾脏显示 GLUTs 1 和 3 的共同主导地位。大多数组织中的 GLUT4 水平相对较低,在白肌中最高,其中 GLUT4 仅占总转录本水平的 12%。由于大西洋鳕鱼中红色肌肉和脂肪组织的含量较低,大多数组织中 GLUT4 转录本的水平可能反映了两个未包含在当前研究中的组织。从 [2-(3)H]-葡萄糖追踪 (3)H2O 产生的速度来确定从分离的气腺、心脏和 RBC 制备的细胞中的葡萄糖代谢率。这三种组织中基础糖酵解的稳态速率与 GLUT1 的相对转录水平相关。
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