Table 1.
Identity of human tubulin isotypes: NCBI accession number, isoelectric point and mass.
| Tubulin isotypea | Accession number NCBI | Protein mass (Da) | pI | C-terminal sequenceb | Mass (Da) CNBr C-terminal peptide |
|---|---|---|---|---|---|
| α1A (α brain specific, hum-a-tub1, hum-a-tub2, α3) | NP_006000 | 50,135.6 | 4.94 | MAALEKDYEEVGVDSVEGEGEEEGEEY | 2860.87 |
| α1B (Kα1, α-tub isoform 1, α1, α-tubulin ubiquitous) | AAC31959 | 50,151.6 | 4.94 | MAALEKDYEEVGVDSVEGEGEEEGEEY | 2860.87 |
| α1C (α6) | Q9BQE3 | 49,895.3 | 4.96 | MAALEKDYEEVGADSADGEDEGEEY | 2590.55 |
| α3Cd (α2) | Q13748 | 49,959.5 | 4.98 | LAALEKDYEEVGVDSVEAEAEEGEEY | 4152.21 |
| α3E | NP_997195 | 49,916.6 | 4.97 | LAALEKDCEEVGVDSVEAEAEEGEEY | 4093.17 |
| α4A (α1 testis specific) | NP_005991 | 49,924.4 | 4.95 | MAALEKDYEEVG I D SYEDEDEGEE | 2633.61 |
| α8 (α-like 2) | Q9NY65 | 50,093.5 | 4.94 | LAALEKDYEEVGTDSFEEENEGEEF | 4158.17 |
| α-like 3 | NP_079079 | 49,908.7 | 5.68 | LAALERDYEEVAQSF | 3060.23 |
| Bα1e (α3) | CAA25855 | 50,157.7 | 5.02 | MAALEKDYEEVGVHSVEGEGEEEGEEY | 2882.93 |
|
| |||||
| βI (β5, β4, Ib) | AAD33873 | 49,670.8 | 4.78 | YQDATAEEEEDFGEEAEEEA | 3367.30 |
| βIIf (class II β-tubulin, β2A / β2B) | NP 001060 / AAH01352 | 49,953.1 / 49,907.0 | 4.78 / 4.78 | YQDATADEQGEFEEEEGEDEA | 3467.38 |
| βIII (β4) | AAH00748 | 50,432.7 | 4.83 | YQDATAEEEGEMYEDDEEESEAQGPK | 1624.58 |
| βIVag (β4, β5) | CAA25318 / NP_006078 | 49,630.9 / 49,585.8 | 4.81 / 4.78 | YQDATAEQGEFEEEAEEEVA YQDATAEEGEFEEEAEEEVA |
3350.36 / 3351.35 |
| βIVb (β2C) | CAA26203 | 49,831.0 | 4.79 | YQDATAEEEGEFEEEAEEEVA | 3480.46 |
| βV (β6) | NP_115914 | 49,857.1 | 4.77 | YQDATANDGEEAFEDEEEE I DG | 3552.49 |
| βVI (β1) | NP_110400 | 50,326.9 | 5.05 | FQDAKAVLEEDEEVTEEAEMEPEDKGH | 809.82 |
Nomenclature of α-tubulin is based on recent revision [15]. Old names used for human tubulin isotypes are indicated in parenthesis.
First amino acid residue has been arbitrarily chosen.
Calculated average [M-H]− mass of the CNBr C-terminal peptides when analyzed by MALDI-TOF in the negative mode.
Another gene coding for the same sequence has been cloned (TUBA3D) [15].
This isotype was not considered in the new α-tubulin nomenclature
Two different sequences were found in the NCBI protein database.
Two βIVa-tubulin sequences with distinct C-termini were found in the NCBI protein database. The upper C-terminal sequence was found in human brain and lower sequence was found in a human oligodendroglioma and in mouse brain.