The dachs gene was first identified almost a century ago based on its requirements for appendage growth, but has been relatively little studied. Here, we describe the phenotypes of strong dachs mutations, report the cloning of the dachs gene, characterize the localization of Dachs protein, and investigate the relationship between Dachs and the Fat pathway. Mutation of dachs reduces, but does not abolish, the growth of legs and wings. dachs encodes an unconventional myosin that preferentially localizes to the membrane of imaginal disc cells. dachs mutations suppress the effects of fat mutations on gene expression, cell affinity and growth in imaginal discs. Dachs protein localization is influenced by Fat, Four-jointed and Dachsous, consistent with its genetic placement downstream of fat. However, dachs mutations have only mild tissue polarity phenotypes, and only partially suppress the tissue polarity defects of fat mutants. Our results implicate Dachs as a crucial downstream component of a Fat signaling pathway that influences growth, affinity and gene expression during development.
Membrane assembly was observed to proceed in cell-free extracts. Specifically, the membrane glycoprotein of vesicular stomatitis virus was synthesized in crude extracts of wheat germ in the presence of membrane vesicles derived from pancreatic endoplasmic reticulum. The glycoprotein (G protein) of vesicular stomatitis virus (VSV) is well suited for such studies. The G protein is found in the plasma membrane of the infected cell, and after budding of the virus from the cell becomes the spike of the mature virion (4-7). Most of the G protein is located external to the viral (8)
Calcium-dependent protein kinase activities have been studied in nerve growth cone particles (GCPs) and compared with those of synaptosomes. GCPs contain a set of phosphoproteins qualitatively similar to that of synaptic nerve terminals. However, major quantitative differences appear to exist: whereas synapsin I phosphorylation is relatively weak, the major kinase substrates of GCPs are a 46,000-dalton membrane protein (calcium/calmodulin dependent) and two acidic proteins of 80,000 and 40,000 daltons, phosphorylated by a calcium/phospholipid-dependent protein kinase. The presence of synaptic kinase activities in GCPs is consistent with their neuronal origin. The role of these kinases in GCPs is not understood at present. They may be involved in growth-related functions and/or may prepare the sprouting neuron for synaptic function.
Antibodies against horseradish peroxidase (anti‐HRP) recognize neural specific cell surface antigens in Drosophila and other insects. The nature of these antigens was investigated in Drosophila and found to include a complex set of developmentally regulated proteins. Their common epitope appears to be a carbohydrate that shares features with the sugar moiety of pineapple stem bromelain, a plant glycoprotein whose carbohydrate structure has been determined. A mutation was identified that eliminates staining by the antibody in imaginal and adult neural tissue. Tissue specific glycoconjugates, although widespread in the animal kingdom, are little understood. This mutation provides a unique opportunity to address the consequences of altering a neural specific carbohydrate moiety in an otherwise intact and behaving animal. The mutation maps to 84F. A second mutation, contained on the third chromosome balancer, TM3, eliminates anti‐HRP staining in embryos. These mutations appear to be separate genes.
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