Previous Article | Next Article ![]()
Mol. Cell. Biol., 09 1997, 5077-5086, Vol 17, No. 9
RA Ach, T Durfee, AB Miller, P Taranto, L Hanley-Bowdoin, PC Zambryski and W Gruissem
Unlike mammalian and yeast cells, little is known about how plants regulate
G1 progression and entry into the S phase of the cell cycle. In mammalian
cells, a key regulator of this process is the retinoblastoma tumor
suppressor protein (RB). In contrast, G1 control in Saccharomyces
cerevisiae does not utilize an RB-like protein. We report here the cloning
of cDNAs from two Zea mays genes, RRB1 and RRB2, that encode RB-related
proteins. Further, RRB2 transcripts are alternatively spliced to yield two
proteins with different C termini. At least one RRB gene is expressed in
all the tissues examined, with the highest levels seen in the shoot apex.
RRB1 is a 96-kDa nuclear protein that can physically interact with two
mammalian DNA tumor virus oncoproteins, simian virus 40 large-T antigen and
adenovirus E1A, and with a plant D-type cyclin. These associations are
abolished by mutation of a conserved cysteine residue in RRB1 that is also
essential for RB function. RRB1 binding potential is also sensitive to
deletions in the conserved A and B domains, although differences exist in
these effects compared to those of human RB. RRB1 can also bind to the AL1
protein from tomato golden mosaic virus (TGMV), a protein which is
essential for TGMV DNA replication. These results suggest that G1
regulation in plant cells is controlled by a mechanism which is much more
similar to that found in mammalian cells than that in yeast.
Copyright © 1997, American Society for Microbiology
RRB1 and RRB2 encode maize retinoblastoma-related proteins that interact with a plant D-type cyclin and geminivirus replication protein
Department of Plant and Microbial Biology, University of California, Berkeley 94720-3102, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»