Cloning, Expression, and Properties of the Microtubule-Stabilizing Protein STOP

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 93; no. 5; pp. 2125 - 2130
• Main Authors: Bosc, Christophe, Cronk, Jeff D., Pirollet, Fabienne, Watterson, Daniel M., Haiech, Jacques, Job, Didier, Margolis, Robert L.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 05.03.1996; National Acad Sciences; National Academy of Sciences
• Subjects: Amino Acid Sequence; Amino acids; Animals; Antibodies; Base Sequence; Biochemistry; Calmodulin - metabolism; Calmodulin-Binding Proteins - genetics; Calmodulin-Binding Proteins - metabolism; Cell lines; Cloning, Molecular; Complementary DNA; Consensus Sequence; DNA, Complementary - genetics; Gene Expression; Generally accepted auditing standards; HeLa Cells; Humans; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Microtubules; Microtubules - metabolism; Molecular Sequence Data; Molecular Weight; Neurons; Protein Binding; Proteins; Rats; Repetitive Sequences, Nucleic Acid; RNA, Messenger - genetics; Transfection
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.93.5.2125

Nerve cells contain abundant subpopulations of cold-stable microtubules. We have previously isolated a calmodulin-regulated brain protein, STOP (stable tubule-only polypeptide), which reconstitutes microtubule cold stability when added to cold-labile microtubules in vitro. We have now cloned cDNA encoding STOP. We find that STOP is a 100.5-kDa protein with no homology to known proteins. The primary structure of STOP includes two distinct domains of repeated motifs. The central region of STOP contains 5 tandem repeats of 46 amino acids, 4 with 98% homology to the consensus sequence. The STOP C terminus contains 28 imperfect repeats of an 11-amino acid motif. STOP also contains a putative SH3-binding motif close to its N terminus. In vitro translated STOP binds to both microtubules and Ca2+-calmodulin. When STOP cDNA is expressed in cells that lack cold-stable microtubules, STOP associates with microtubules at 37 degrees C, and stabilizes microtubule networks, inducing cold stability, nocodazole resistance, and tubulin detyrosination on microtubules in transfected cells. We conclude that STOP must play an important role in the generation of microtubule cold stability and in the control of microtubule dynamics in brain.