The observation that IC74 co-sediments mainly with dynein heavy chain 1a (DHC1a) but not with DHC1b isoforms suggests that the dynein isotype that may be associated with spermatid translocation is the DHC1a form. buy birth control online
The most likely position of any dynein related to the junction plaques is on the cytoplasmic face of the endoplasmic reticulum component of the structures. The endoplasmic reticulum is the component of each plaque that is related to microtubules in vivo and is the component of the plague that binds microtubules in vitro. Moreover, there is much precedent for motor proteins being related to endoplasmic reticulum in general in cells. Localization of the motor at the ultrastructural level is needed to settle this issue and to determine other organelles with which the motor may be associated in Sertoli cells.
As reported for invertebrate sperm, kinesin-II in rat spermatids is localized to the flagellum. Striking immunofluorescence was seen in the developing flagella of spermatids when tissue sections were exposed to the kinesin-II antibody. Intensely staining structures observed near the base of the spermatid tails may be the flagellar homologues of basal bodies in cilia; however, this remains to be confirmed electron-microscopically.