Amino-acid sequence data of beta-tubulin from Physarum polycephalum myxamoebae.

Starting with 7.7 mg of a beta-tubulin isolated from myxamoebae of the slime mould Physarum polycephalum, 90% of the sequence has been determined by the Edman degradation of peptides generated by cyanogen bromide, trypsin and Staphylococcus aureus protease. Differences to other beta-tubulins are mainly conservative and spread evenly throughout the chain except for a high concentration at the C-terminus. The Physarum beta-tubulin shows most homology to Chlamydomonas beta-tubulin (90.5%) and least homology to yeast beta-tubulin (S. cerevisiae, 73.4%). Two tryptic peptides were isolated in approximately equal quantities which were identical except in one position (S/ALTVPELTQRMFDA) showing that at least two beta-tubulins are present in myxamoebae. However, since this was the only heterogeneity found, these beta-tubulins are probably very similar.