# Cannot dock RNA-Protein complex

**URL:** https://ask.bioexcel.eu/t/cannot-dock-rna-protein-complex/872
**Category:** HADDOCK
**Created:** [April 2, 2018, 7:26pm UTC](https://ask.bioexcel.eu/t/cannot-dock-rna-protein-complex/872 "2018-04-02T19:26:32Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Sampurna\_Mukherjee](https://avatars.discourse-cdn.com/v4/letter/s/b5ac83/32.png) [@Sampurna\_Mukherjee](https://ask.bioexcel.eu/u/Sampurna_Mukherjee)
#### Post date: [April 2, 2018, 7:26pm UTC](https://ask.bioexcel.eu/t/cannot-dock-rna-protein-complex/872/1 "2018-04-02T19:26:33Z")

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Hi.  
I am using RNA structures generated by the MC-Sym|MC-Fold algorithm and docking it with ER-alpha receptor protein(PDB ID:1SJ0).  
I am getting the following error:  
There was an inconsistency in your data

Error message

Second pdb file contains an unknown amino acid or nucleic acid base C

Make sure to use three letter code for bases and amino acid

* * *

Can anybody inform me as to what is wrong? Thank you.

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### Author: ![amjjbonvin](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/amjjbonvin/32/23_2.png) [@amjjbonvin](https://ask.bioexcel.eu/u/amjjbonvin)
#### Post date: [April 3, 2018, 8:59am UTC](https://ask.bioexcel.eu/t/cannot-dock-rna-protein-complex/872/2 "2018-04-03T08:59:45Z")

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As the error message says: Use a three letter code for your RNA, i.e. ADE, CYT, URI, …