problem in protein expression

Duncan Clark junk at hgmp.mrc.ac.uk
Thu Jul 3 05:16:53 EST 2003


Historians believe that in newspost 
<bduluf$2lpo$1 at justice.itsc.cuhk.edu.hk> on Wed, 2 Jul 2003, SCK 
<holap7c at hotmail.com> penned the following literary masterpiece:
>I'm sure it has these two
>
>"EK" <nobody at elnino.com> ¦b¶l¥ó news:HPZLa.16$U4.10548 at news.uchicago.edu ¤¤
>¼¶¼g...
>>
>> "SCK" <holap7c at hotmail.com> wrote in message
>> news:bdplir$e5e$1 at justice.itsc.cuhk.edu.hk...
>> > Several homologus proteins have been cloned and tried to express in E.
>> coli.
>> > However, several of them were expressed in a size much larger than
>> expected
>> > as detected by SDS-PAGE. What may be the causes for that?
>> >
>> >
>> No stop codon + no transcription terminator ?
>> - EK
>>
>>
>>

If you are sure your SDS gel really is denaturing then you have either 
cloned a larger ORF than you think or you don't have a stop codon and 
are cloned in frame with plasmid DNA so generate a fusion or you have 
protein that runs at an anomalous mwt from that predicted. Sequencing is 
the key.

Duncan
-- 
I love deadlines. I especially like the whooshing noise they make as
they go flying by.

Duncan Clark
GeneSys Ltd.



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