Proteasomes regulate the motility of salmonid fish sperm through modulation of cAMP-dependent phosphorylation of an outer arm dynein light chain.
Proteasomes are involved in ATP-dependent regulation of sperm motility in salmonid fish. We have demonstrated here by immunoelectron microscopy that proteasomes are located at the structure of the chum salmon sperm flagellum that attaches at the base of the outer arm dynein and extends toward the plasma membrane. Furthermore, substrates and inhibitors of proteasome inhibit the cAMP-dependent phosphorylation of a 22 kDa axonemal protein in chum salmon sperm. The 22 kDa phosphoprotein was solubilized by treatment of the axoneme with a high salt solution and subsequent sucrose density gradient centrifugation of the extract revealed that it cosedimented with 19 S outer arm dynein, indicating that it is a dynein light chain. These results suggest that proteasomes modulate the activity of outer arm dynein by regulating cAMP-dependent phosphorylation of the 22 kDa dynein light chain.
Inaba
K
K
Misaki Marine Biological Station, Graduate School of Science, University of Tokyo, Miura, Kanagawa, Japan.
Morisawa
S
S
Morisawa
M
M
D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004398:Dyneins / Q000032:analysis / Q000378:metabolism*; D008297:Male; D016253:Microscopy, Immunoelectron; D009097:Multienzyme Complexes / Q000378:metabolism*; D017685:Oncorhynchus keta; D017686:Oncorhynchus mykiss; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex; D013082:Sperm Tail / Q000737:chemistry* / Q000201:enzymology* / Q000648:ultrastructure; D013379:Substrate Specificity
D009097:Multienzyme Complexes; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D004398:Dyneins