SEQUENCES IN THE MYOSIN-II TAIL REQUIRED FOR SELF-ASSOCIATION

The assembly of myosin II molecules into a filament requires the elect rostatic interaction of a domain localized toward the carboxyl-terminu s of the myosin II tail. However, the precise sequences involved in th is interaction are not known. Here we show that the smallest Dictyoste lium myosin II fragment that is necessary and sufficient for self-asso ciation is a fragment of 294 amino acids that contains four clusters o f positively charged and negatively charged residues. Fragments of the same length but which lack one of these positively or negatively char ged clusters are incapable of self-assembly. We postulate that this as sembly domain is also found in myosin II from other species. Such char ged clusters are found in a similar location in rabbit myosin II and a re also essential for filament formation. (C) 1996 Academic Press, Inc .