Liao K, Lane M D
Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Biochem Biophys Res Commun. 1995 Mar 28;208(3):1008-15. doi: 10.1006/bbrc.1995.1434.
A cDNA encoding a novel insulin-activated adipocyte amino acid transporter (designated AAAT) was cloned from a mouse 3T3-L1 adipocyte library. The deduced amino acid sequence of the cDNA corresponds to a protein of 553 amino acids that possesses 56% amino acid sequence identity to the human neutral amino acid transporter and 42% identity to the rat brain glutamate transporter. Transient transfection of 3T3-L1 preadipocytes with an AAAT expression vector led to insulin-dependent uptake of L-serine and to a lesser extent, uptake of L-alanine and L-glutamate. Expression of the AAAT message is tissue-specific, with the highest level occurring in mouse adipose tissue and a lower level in lung. Unlike other sodium-dependent amino acid transporter mRNAs, the AAAT message is not expressed in brain, kidney, liver or heart and only traces are detected in spleen, thymus and skeletal muscle. Consistent with its high level in adipose tissue, expression of the AAAT message is markedly increased when 3T3-L1 preadipocytes are induced to differentiate into adipocytes.
从一个小鼠3T3-L1脂肪细胞文库中克隆出了一个编码新型胰岛素激活脂肪细胞氨基酸转运体（命名为AAAT）的cDNA。该cDNA推导的氨基酸序列对应于一个由553个氨基酸组成的蛋白质，该蛋白质与人类中性氨基酸转运体的氨基酸序列一致性为56%，与大鼠脑谷氨酸转运体的一致性为42%。用AAAT表达载体瞬时转染3T3-L1前脂肪细胞会导致L-丝氨酸的胰岛素依赖性摄取，在较小程度上也会导致L-丙氨酸和L-谷氨酸的摄取。AAAT信息的表达具有组织特异性，在小鼠脂肪组织中水平最高，在肺中水平较低。与其他钠依赖性氨基酸转运体mRNA不同，AAAT信息在脑、肾、肝或心脏中不表达，在脾、胸腺和骨骼肌中仅检测到微量表达。与其在脂肪组织中的高表达水平一致，当3T3-L1前脂肪细胞被诱导分化为脂肪细胞时，AAAT信息的表达显著增加。
