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Smaug is a
''miR-309''
is needed for destabilization of 410 maternal mRNAs. In smaug mutants almost 85% of maternal mRNA is found to be stable. Smaug also binds to 3′ untranslated region (UTR) elements known as ''SMG response elements'' (SREs) on ''nanos'' mRNA and represses its expression by recruiting a protein calle
Cup
''(an eIF4E-binding protein that blocks the binding of eIF4G to eIF4E)''. There after it recruits deadenylation complex CCR4-Not on to the nanos mRNA which leads to deadenylation and subsequent decay of the mRNA.{{Cite journal, last1=Zaessinger, first1=Sophie, last2=Busseau, first2=Isabelle, last3=Simonelig, first3=Martine, date=November 2006, title=Oskar allows nanos mRNA translation in Drosophila embryos by preventing its deadenylation by Smaug/CCR4, journal=Development , volume=133, issue=22, pages=4573–4583, doi=10.1242/dev.02649, issn=0950-1991, pmid=17050620, doi-access=free It is also found to be involved in degradation and repression of materna
Hsp83
mRNA by recruiting CCR4/POP2/NOT deadenylase to the mRNA. The human Smaug protein homologs are SAMD4A and SAMD4B.
Mechanisms of the ''Drosophila'' Mid-blastula Transition
Hsp83 Heat shock protein 83
smg- Protein Smaug - Drosophila by Uniprot
RNA-binding proteins Things named after Tolkien works
Smaug is a RNA-binding protein
RNA-binding proteins (often abbreviated as RBPs) are proteins that bind to the double or single stranded RNA in cells and participate in forming ribonucleoprotein complexes.
RBPs contain various structural motifs, such as RNA recognition motif ( ...
in ''Drosophila
''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...
'' that helps in maternal to zygotic transition Maternal to zygotic transition (MZT, also known as Embryonic Genome Activation) is the stage in embryonic development during which development comes under the exclusive control of the zygotic genome rather than the maternal (egg) genome. The egg con ...
(MZT). The protein is named after the fictional character Smaug
Smaug () is a dragon and the main antagonist in J. R. R. Tolkien's 1937 novel ''The Hobbit'', his treasure and the mountain he lives in being the goal of the quest. Powerful and fearsome, he invaded the Dwarf kingdom of Erebor 150 years prior ...
, the dragon in J.R.R. Tolkien
John Ronald Reuel Tolkien (, ; 3 January 1892 – 2 September 1973) was an English writer and philologist. He was the author of the high fantasy works ''The Hobbit'' and ''The Lord of the Rings''.
From 1925 to 1945, Tolkien was the Rawlins ...
's 1937 novel '' The Hobbit''. The MZT ends with the midblastula transition In developmental biology, midblastula or midblastula transition (MBT) occurs during the blastula stage of embryonic development in non-mammals. During this stage, the embryo is referred to as a blastula. The series of changes to the blastula that ch ...
(MBT), which is defined as the first developmental event in ''Drosophila'' that depends on zygotic mRNA. In ''Drosophila'', the initial developmental events are controlled by maternal mRNAs like ''Hsp83'', '' nanos'', ''string'', ''Pgc'', and '' cyclin B'' mRNA. Degradation of these mRNAs, which is expected to terminate maternal control and enable zygotic control of embryogenesis, happens at interphase of nuclear division cycle 14. During this transition smaug protein targets the maternal mRNA for destruction using miRs
Hot Mobile ( he, הוט מובייל, formerly known as Mirs Communications Ltd. until May 2012), is a wireless telecommunications company based in Israel and a subsidiary of Hot Telecommunication Systems Ltd. (HOT).
Hot Mobile provides nationwid ...
. Thus activating the zygotic genes. Smaug is expected to play a role in expression of three miRNAs – ''miR-3, miR-6, miR-309'' and ''miR-286'' during MZT in ''Drosophila''. Among them smaug dependent expression o''miR-309''
is needed for destabilization of 410 maternal mRNAs. In smaug mutants almost 85% of maternal mRNA is found to be stable. Smaug also binds to 3′ untranslated region (UTR) elements known as ''SMG response elements'' (SREs) on ''nanos'' mRNA and represses its expression by recruiting a protein calle
Cup
''(an eIF4E-binding protein that blocks the binding of eIF4G to eIF4E)''. There after it recruits deadenylation complex CCR4-Not on to the nanos mRNA which leads to deadenylation and subsequent decay of the mRNA.{{Cite journal, last1=Zaessinger, first1=Sophie, last2=Busseau, first2=Isabelle, last3=Simonelig, first3=Martine, date=November 2006, title=Oskar allows nanos mRNA translation in Drosophila embryos by preventing its deadenylation by Smaug/CCR4, journal=Development , volume=133, issue=22, pages=4573–4583, doi=10.1242/dev.02649, issn=0950-1991, pmid=17050620, doi-access=free It is also found to be involved in degradation and repression of materna
Hsp83
mRNA by recruiting CCR4/POP2/NOT deadenylase to the mRNA. The human Smaug protein homologs are SAMD4A and SAMD4B.
References
External links
Mechanisms of the ''Drosophila'' Mid-blastula Transition
Hsp83 Heat shock protein 83
smg- Protein Smaug - Drosophila by Uniprot
RNA-binding proteins Things named after Tolkien works