But phase flipping would probably not provide any practical advantage over
full CTF correction except for the lowest frequencies (ignore until first
peak option), while throwing away part of information at higher
frequencies.
S
> Hi,
>
> Phase flip only may also work.
>
> Best wishes,
> Reza
>
> Reza Khayat, PhD
> Assistant Professor
> Department of Chemistry
> City College of New York
> 85 Saint Nicholas Terrace, CDI 2.318
> New York, NY 10031
> http://www.khayatlab.org/
> 212-650-6070
>
> -----Original Message-----
> From: Collaborative Computational Project in Electron cryo-Microscopy
> [mailto:[log in to unmask]] On Behalf Of Sjors Scheres
> Sent: Wednesday, July 19, 2017 9:59 AM
> To: [log in to unmask]
> Subject: Re: [ccpem] difficulty aligning small particles
>
> Hi Joel,
> You could try to ignore the CTFs until their first peak (on the CTF tab).
> HTH,
> Sjors
> On 07/19/2017 02:33 PM, Joel Meyerson wrote:
>> Hi,
>> I'm working with a 170 kDa membrane protein imaged on a Krios/K2. In
>> the micrographs the particles have the expected features, and they
>> adopt multiple orientations.
>>
>> I manually picked ~12,000 particles and tried 2D classification in
>> Relion 2.1, but the particles seem to collapse into just a few classes
>> with poorly defined features. I tested a range of mask diameters, and
>> also tried limiting the expectation step resolution to 10 A, but the
>> classes did not improve.
>>
>> Are there other tips out there for working with smaller proteins?
>>
>> Thanks,
>> Joel
>
> --
> Sjors Scheres
> MRC Laboratory of Molecular Biology
> Francis Crick Avenue, Cambridge Biomedical Campus Cambridge CB2 0QH, U.K.
> tel: +44 (0)1223 267061
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www2.mrc-2Dlmb.cam.ac.uk_groups_scheres&d=DwICaQ&c=4NmamNZG3KTnUCoC6InoLJ6KV1tbVKrkZXHRwtIMGmo&r=1DzJFW0v6TgEhkW1gy_-ke-RbtvS1fzEbD5_hcb9Up0&m=Ht9FXzAXTiW28ZPLrjY6JTUwef7fqh6vjV760V1CcXg&s=wqTf9G8GI-PXV2MWdLJ1znyc-3QrnKyc-MfNG2JeXJ0&e=
>
--
Sjors Scheres
MRC Laboratory of Molecular Biology
Francis Crick Avenue, Cambridge Biomedical Campus
Cambridge CB2 0QH, U.K.
tel: +44 (0)1223 267061
http://www2.mrc-lmb.cam.ac.uk/groups/scheres
|