discrepancies between cDNA and protein sequences

[Cornelius Krasel]

Le Pennec Jean-Paul (lepennec at univ-rennes1.fr) wrote:
> I have analysed a cDNA sequence of a protein already sequenced by 
> chemical-physical analysis and I get differences of the amino acids 
> composition. I'd like  to know wether i can trust 100 % the protein 
> analysis or go back to my sequence.What do you think? I am looking 
> forward hearing from you !

Maybe you can explain the differences by posttranslational processing
of the polypeptide chain? This would probably explain only rather
small differences (except if there is a big proteolytic cut, but then
you should be able to see a difference between apparent MW on SDS-PAGE
and calculated MW from the sequence). Big differences could be explained
by frameshift errors in the cDNA sequence. (Of course amino acid
sequencing is not fool-proof either.)

--Cornelius.

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