• Molecular Biology of Amino Acid and Peptide Transport Systems

      Li, Huiwu; Georgia Cancer Center (1999)
      (First Paragraph) Amino acids are essential components in cellular metabolism. Some of these amino acids can be synthesized within the cells from other biological molecules and these amino acids are termed ‘nonessential’. These ‘nonessential’ amino acids are alanine, aspartate, cysteine, glutamate, glycine, pro line, serine, tyrosine, glutamine and asparagine. In contrast, some amino acids cannot be synthesized endogenously and have to be supplied in the diet (1). These amino acids are termed ‘essential’. These ‘essential’ amino acids are histidine, arginine, leucine, isoleucine, lysine, methionine, threonine, phenylalanine, tryptophan, and valine. Mammalian cells require ‘essential’ as well as ‘nonessential’ amino acids for their metabolic activity. Even though the cells can synthesize the ‘nonessential’ amino acids to some extent, most of the amino acids have to be supplied to the cells via specific membrane transport mechanisms.