Four repeat MAP2 isoforms in human and rat brain.
In mammalian brain, variations in the primary structure of the characterized microtubule-associated protein 2 (MAP2) isoforms have only been observed in their projection domains whose length determines the spacing between neighboring microtubules. We now report that, as with MAP4 and tau, MAP2 isoforms containing four (4R) instead of three (3R) tandem repeats in their microtubule binding domains do exist in human and rat brain. The additional sequence, inserted between the first and second repeat of the 3R-MAP2 messages, appears on mRNAs encoding both high and low molecular weight (Hwt and Lwt) rat MAP2 variants. In contrast to the corresponding 3R-messages, 4R-Hwt MAP2 concentrations decrease during early postnatal rat brain development, while the amount of 4R-Lwt MAP2 messages remains constant. In general, 4R-/3R-MAP2 mRNA ratios appear to be low with the highest levels of 4R-messages found in the cerebellum.
Kindler
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California Institute of Technology, Division of Biology 216-76, Pasadena 91125.
Garner
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D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D002531:Cerebellum / Q000378:metabolism; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D015723:Gene Library; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense; D009928:Organ Specificity; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis*; D051381:Rats; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D008869:Microtubule-Associated Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger