Contains Khc sequences in which four basic amino acids in the tail microtubule-binding region have been mutated to neutral alanines (amino acid replacements K925A, R929A, H932A, and R936A).
Khc4R-A in a Khc27/Df(2R)Jp6 background results in 50% lethality before the end of the third larval instar and axonal mitochondria flux is reduced approximately 30-fold. One copy of Khc4R-A fully rescues fast ooplasmic streaming in Khc27 oocytes.