kelompok 7 signal-transduction

8/17/2019 Kelompok 7 Signal-Transduction

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Signal TransductionMusiyam

Fatimatuz Zahroh

Rizky Budiono Putri

Ronal Yoki Saputra

Ramadyan Tefarani


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Introductionharles !ar"in performed pioneering studies on

phototropic gro"th responses in canary grass and oat

seedling tissue #!ar"in $%%$&'Since these classic studies( researchers ha)e

demonstrated that plants percei)e many en)iromental and

physiological signals in order to fine*tune gro"th and

de)elopment'Plant cells percei)e these e+ternal and internal signals ,y

employing specialized sensor protein termed receptors'

-ne receptors sense their spesific signal( they must

transduce signal #i'e'( con)ert it from one form to another&in order to amplify the signal and trigger the cellular

respons'

.ll signal transduction path"ays typically in)ol)e the

folo"ing chain of e)ents /

signal 0 receptor 0 signal transduction 0 response


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Signal Transduction in Plant and

.nimal ells Plants and animals employ distinct sets of signals to regulate

their de)elopment'

1+ample #plants& / germination( leaf formation( and flo"ering

are regulated ,y en)iromental signals #such as temperature(

light( and day length&'

1+ampel #animals& de)elopment is generally regulated ,y

physiological #i'e'( internal& signal'


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Plants and .nimals ha)e similar transduction

components

Plants and animals share many similarities at the le)el of

their signal transduction machinery'

For e+ample / plant and animal cells use common

secondary messengers( like calcium( lipid signaling

molecules( and p2 changes( to trigger physiological

respones #figure $3'$&


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4am,ar $3'$


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Plants and animals also employ large num,ers of kinase

receptors and kinase signal transduction proteins'

5inase receptors and kinase signal transduction proteins

ha)e kinase acti)ity as "ell as functioning as signal

receptors or intermedietes in transduction path"ays'

Plant and animal receptor kinase are often localized at the

plasma mem,rane( "here they are ideally positioned the

directly detect e+tracellular signals'


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4am,ar $3'6 a dan $3'6 ,


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Receptor kinase can initiate a signal

transduction cascade Receptor kinase must modify the acti)ity of other proteins in

order to trigger an intracellular signal transductioncascade' . target protein can ,e phosphorylated at )arious

amino acid residues #serine( threonine( tyrosine( or histidine&

-ne of the key functions of a kinase cascade is to amplify the

original receptor signaling e)ent at the plasma mem,rane'

1ach kinase that is phosphorylated "ill modify the acti)ity of

many more of its o"n target proteins'


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. signaling cascade composed of se)eral kinase "ill

therefore ,e a,le to alter the phosphorylation status of tensor thousands of target proteins in response to relati)ely fe"

ligand molecules originally ,inding the receptor at the plasma

mem,rane'

Modification of the acti)ities of protein kinase ultimately

causes changes to gene e+pression'


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In addition to kinase( enzymes that remo)e phsophate

groups from proteins( protein phosphatase, play importantroles "ithin signal transduction path"ays'

In summary( plants and animals employ receptors in

con7untion "ith kinase and phosphatase transduction

components in a num,er of important signaling path"ays'

Figure $3'8 a

Figuer $3'8 ,


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Figure $3'8 a dan $3'8 ,


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Plants signal transduction components ha)e

en)ol)ed from ,oth prokaryotic and eukaryotic

ancetors

.nimal genome s often contain hundreds of G-protein-

coupled receptors (GPCRs) that detect a di)erse array ofsignals ranging from hormones( odors( fla)ors( and e)en

light' 4PRs signal )ia hetero*trimeric 4 proteins( "hich are

encoded ,y a large num,er of genes'

In contrast( no plant 4PRs ha)e ,een functionally identified

to date' Moreo)er( only on copies of hetero trimeric 4 proteingenes ha)e identified in the .ra,idopsis genome #9ones and

.ssmann 6::3&'


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-ne of the main reasons the higher plants ha)e a distinct

repertoire of signal transduction components is that theyha)e e)ol)ed from ,oth prokaryotic and eukaryotic'

Plants ha)e utilized signaling components from ,oth their

single 0cell eukaryotic progenitor and the prokaryotic

precursor of the chloroplast'


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The .ra,idopsis denome includes t"o cryptochrome* related

genes #YR$ and YR6&' ryptochrome are ,acterial fla)oproteins that function as

!;. photolyases that repair pyrimidine dimer produced ,y


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4am,ar $3'3


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Signal are preci)ied at many

locations "ithin plant cells Plants can percie)e e+ternal signals at many locations "ithin

their cells' 1+ample( light detected ,y distinct classes ofphotoreceptors at the plasma mem,rane and in the

cytoplasm and nucleus #figure $3'?&


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4am,ar $3'?


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Plant signal transduction often

in)ol)es inacti)ation of repressor

proteins

Figure $3'@ a' ,' c

kelompok 7 signal-transduction

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