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>Divergent neural β tubulin from the antarctic fishnotothenia coriiceps neglecta: Potential sequence contributions to cold adaptation of microtubule assembly
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Divergent neural β tubulin from the antarctic fishnotothenia coriiceps neglecta: Potential sequence contributions to cold adaptation of microtubule assembly
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机译：Divergent neural β tubulin from the antarctic fishnotothenia coriiceps neglecta: Potential sequence contributions to cold adaptation of microtubule assembly
AbstractThe cytoplasmic microtubules of the cold‐adapted Antarctic fishes, unlike those of homeotherms and temperate poikilotherms, assemble and function at body temperatures in the range −1.8 to +2°C. To determine whether alterations to the primary sequence of β tubulin may contribute to enhancement of microtubule assembly at cold temperatures, we have cloned and sequenced a 1.8‐kilobase neural β‐chain cDNA, Ncnβ1, from an Antarctic rockcod,Notothenia coriiceps neglecta. Based on nucleotide sequence homology, Ncnβ1 probably corresponds to a class‐II β‐tubulin gene. The 446‐residue β chain encoded by Ncnβ1 is closely related (sequence homology ∼95) both to the neural class‐I/II isotypes and to the neural/testicular class‐IV variants of higher vertebrates, but the sequence of its carboxy‐terminal isotype‐defining region (residues 431–446) has diverged markedly (≥ 25 change relative to the I/II/IV referents). Furthermore, the NcnβsZ1 polypeptide contains six unique amino‐acid substitutions (five conservative, one nonconservative) not found in other vertebrate brain isotypes, and the carboxyterminal region possesses a unique tyrosine inserted at position 442. We conclude that Ncnβ1 encodes a class‐II β tubulin that contains sequence modifications, located largely in its interdimer contact domain, that may contribute to cold adaptation of mi
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