Taxonomic distribution of proteins containing Robl_LC7 domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing Robl_LC7 domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Site-specific recognition of a 70-base-pair element containing d(GA)(n)repeats mediates bithoraxoid polycomb group response element-dependentsilencing.

Hodgson JW, Argiropoulos B, Brock HW
Mol Cell Biol. 2001; 21: 4528-43

Polycomb group proteins act through Polycomb group response elements(PREs) to maintain silencing at homeotic loci. The minimal 1.5-kbbithoraxoid (bxd) PRE contains a region required for pairing-sensitiverepression and flanking regions required for maintenance of embryonicsilencing. Little is known about the identity of specific sequencesnecessary for function of the flanking regions. Using gel mobility shiftanalysis, we identify DNA binding activities that interact specificallywith a multipartite 70-bp fragment (MHS-70) downstream of thepairing-sensitive sequence. Deletion of MHS-70 in the context of a 5.1-kbbxd Polycomb group response element derepresses maintenance of silencingin embryos. A partially purified binding activity requires multiple,nonoverlapping d(GA)(3) repeats for MHS-70 binding in vitro. Mutation ofd(GA)(3) repeats within MHS-70 in the context of the 5.1-kb bxd PREdestabilizes maintenance of silencing in a subset of cells in vivo butgives weaker derepression than deletion of MHS-70. These results suggestthat d(GA)(3) repeats are important for silencing but that other sequenceswithin MHS-70 also contribute to silencing. Antibody supershift assays andWestern analyses show that distinct isoforms of Polyhomeotic and twoproteins that recognize d(GA)(3) repeats, the TRL/GAGA factor andPipsqueak (Psq), are present in the MHS-70 binding activity. Mutations inTrl and psq enhance homeotic phenotypes of ph, indicating that TRL/GAGAfactor and Psq are enhancers of Polycomb which have sequence-specific DNAbinding activity. These studies demonstrate that site-specific recognitionof the bxd PRE by d(GA)(n) repeat binding activities mediatesPcG-dependent silencing.

Dynein light chains of the Roadblock/LC7 group belong to an ancientprotein superfamily implicated in NTPase regulation.

Koonin EV, Aravind L
Curr Biol. 2000; 10: 7746-7746

Drosophila roadblock and Chlamydomonas LC7: a conserved family ofdynein-associated proteins involved in axonal transport, flagellarmotility, and mitosis.

Bowman AB, Patel-King RS, Benashski SE, McCaffery JM, Goldstein LS, King SM
J Cell Biol. 1999; 146: 165-80

Eukaryotic organisms utilize microtubule-dependent motors of the kinesinand dynein superfamilies to generate intracellular movement. To identifynew genes involved in the regulation of axonal transport in Drosophilamelanogaster, we undertook a screen based upon the sluggish larvalphenotype of known motor mutants. One of the mutants identified in thisscreen, roadblock (robl), exhibits diverse defects in intracellulartransport including axonal transport and mitosis. These defects includeintra-axonal accumulations of cargoes, severe axonal degeneration, andaberrant chromosome segregation. The gene identified by robl encodes a97-amino acid polypeptide that is 57% identical (70% similar) to the105-amino acid Chlamydomonas outer arm dynein-associated protein LC7, alsoreported here. Both robl and LC7 have homology to several other genes fromfruit fly, nematode, and mammals, but not Saccharomyces cerevisiae.Furthermore, we demonstrate that members of this family of proteins areassociated with both flagellar outer arm dynein and Drosophila and ratbrain cytoplasmic dynein. We propose that roadblock/LC7 family members maymodulate specific dynein functions.

Gliding motility in Myxococcus xanthus: mgl locus, RNA, and predictedprotein products.

Stephens K, Hartzell P, Kaiser D
J Bacteriol. 1989; 171: 819-30

Mutants of Myxococcus xanthus that had lost the ability to glide wereexamined to elucidate the mechanism of gliding motility. Nonmotile mutantsresulting from a single mutational step were all defective at the samelocus, mgl, which implied an important role for the mgl product(s) ingliding. Deletion experiments, transposon insertion mutagenesis, andgenetic rescue of mgl mutants mapped the locus to a 1.6-kilobase segmentof Myxococcus DNA. Two species of RNA that hybridized with mgl DNA werefound both during vegetative growth and during the starvation-induceddevelopment of fruiting bodies, which also requires cell movement. The twoRNA species, of 1.5 and 1.3 kilobases, had the same 5' to 3' orientationand overlapped extensively. The DNA sequences of mgl+ and of seven mglmutants were determined. Each mutant differed from mgl+ by asingle-base-pair change in the sequence. Two adjacent open reading frameswere found in the sequence hybridizing to both species of mgl RNA. Six ofthe single-base-pair changes, each of which would result in asingle-amino-acid change, and an insertion-produced mgl mutation werelocated in the downstream open reading frame. This open reading frame (of195 amino acids) is therefore an mgl gene, called mglA. The function ofthe upstream open reading frame is not known with certainty, although itdoes contain one of the mgl mutant sites and could be a second mgl gene.