Arthrin, a myofibrillar protein of insect flight muscle, is an actin-ubiquitin conjugate.
Flight muscles of some insects contain a myofibrillar protein termed arthrin, which is closely related to actin (mw 43,000). Here we demonstrate that arthrin (mw 55,000) is ubiquitinated actin. We show that in Act88FM342, a flightless Drosophila mutant wherein the Act88F actin gene specifies a glu93----lys replacement, isoelectric points of both actin III and arthrin are shifted, revealing that both are encoded by the same gene. Arthrin reacts with an anti-ubiquitin antibody, which demonstrates that its extra mass results from ubiquitin ligation. Approximately one-seventh of myofibrillar actin is stably ubiquitinated, suggesting that there may be one arthrin molecule per actin-tropomyosin-troponin cooperative unit. Arthrin formation lags several hours behind that of actin III, implying that ubiquitination coincides with some aspect of myofibril assembly.
Ball
E
E
Department of Biology, University of York, England.
Karlik
C C
CC
Beall
C J
CJ
Saville
D L
DL
Sparrow
J C
JC
Bullard
B
B
Fyrberg
E A
EA
D000199:Actins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D004330:Drosophila; D005426:Flight, Animal; D005796:Genes; D005815:Genetic Code; D005838:Genotype; D019476:Insect Proteins; D007313:Insecta / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008840:Microfilament Proteins / Q000096:biosynthesis / Q000235:genetics*; D009124:Muscle Proteins / Q000096:biosynthesis / Q000235:genetics*; D009154:Mutation; D013997:Time Factors; D025801:Ubiquitin; D014452:Ubiquitins / Q000235:genetics* / Q000378:metabolism
D000199:Actins; D019476:Insect Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D025801:Ubiquitin; D014452:Ubiquitins; C045830:arthrin