The deduced amino acid sequences of human platelet and frontal cortex monoamine oxidase B are identical.
Monoamine oxidases (MAOs) A and B play important roles in the metabolism of neuroactive, vasoactive amines. Human platelets contain only MAO B, often used as an indicator of brain MAO B. The validity of this model remained to be evaluated. This report describes the molecular cloning of human MAO B from frontal cortex and platelets. Two overlapping PCR-amplified clones of human platelet MAO B and four PCR-amplified clones of human frontal cortex MAO B covering the entire coding region were sequenced using five internal oligomers and M13 reverse and forward primers. The nucleotide sequences of human MAO B cDNA from platelet and frontal cortex were identical to that of human liver MAO B except for three nucleotides that differed in frontal cortex: nucleotides 440 A-->G, 794 C-->T, and 825 C-->T. Whether or not these differences are artifactual, all three represent silent mutations, which would not alter the amino acid of the encoded polypeptides. Thus, the deduced amino acid sequences of MAO B from frontal cortex, platelet, and liver are identical. These findings indicate the validity of using platelet MAO B mRNA as a marker for brain MAO B and provide a new approach to study the role of brain MAO B in humans.
Chen
K
K
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles 90033.
Wu
H F
HF
Shih
J C
JC
D000595:Amino Acid Sequence; D001483:Base Sequence; D001792:Blood Platelets / Q000201:enzymology*; D005625:Frontal Lobe / Q000201:enzymology*; D006801:Humans; D008969:Molecular Sequence Data; D008995:Monoamine Oxidase / Q000235:genetics*; D016133:Polymerase Chain Reaction
D008995:Monoamine Oxidase