GUP3 (GPS) Application instructions

Grid Preparation and Screening Overview

The objective of Grid Preparation and Screening (GPS) access is primarily to support groups who have limited experience with cryoEM methods and limited access to local facilities and resources. This GPS service is currently delivered in two ways:

(1) By having users visit NCCAT for a period of 3-4 days, where they would work closely with NCCAT staff to optimize sample and grid preparation conditions, and whenever possible obtain preliminary cryoEM processed data. During their visits, users will be introduced to and receive basic training in cryoEM methods and make use of NCCAT’s resources to screen their samples assisted by expert microscope operators. The goal for each visit will be for users to leave with a clear idea of the next steps needed to advance towards obtaining a Krios-ready sample.

(2) Users who are able to freeze their own grids but do not have access to a screening microscope can apply for Glacios screening only, which is offered as a 1-day session on our Glacios microscope with automated screening with Smart Leginon. A maximum of 24 grids can be screened during this session, and your grids can be returned to you or forwarded to Krios access at NCCAT.

For your information, there are three (3) types of general user proposals:

  • GUP1 (Krios): Data Collection
    Access for experienced users with pre-screened cryoEM samples in need of high-end instrument cryoEM time. For more information go here and to apply for this category of access go here.
  • GUP2 (Chameleon): Chameleon access
    Access for blot free vitrification with the intent of a follow on high-end instrumentation session. Use of Chameleon needs to be justified. For more information go here and to apply for this category of access go here.
  • GUP3 (GPS): Grid preparation and screening
    Access for users in need of staff-assisted sample preparation and screening resources. The preliminary data and grids may then be used to apply for GUP1 Data Collection Access or GUP2 for Chameleon access.


Accepted NCCAT users (and their PI’s if applicable) are required to sign a written agreement that they will comply with all NIH data sharing, reporting and publication policies. The written agreement will also outline other requirements and policies for NCCAT access so as to manage expectations as transparently as possible.

Please email us at if you have any questions or would like more information.

Application process

Applications will be limited to no more than 2 pages of text (1 ideally) and 1 page of supporting data and figures. Key personnel named in the application must also submit an NIH Biosketch (

Researchers will be required to provide biochemical characterization showing the current condition of the sample and indicate the readiness for cryoEM experiments. Applications for on-site visits will cover up to 3 samples for 1 main visit and 1 potential additional visit over a maximum 2 year lifetime for the proposal. The focus will be on a lead user attending all visits to the center for continuity, but additional members of the same laboratory may join or substitute as needed. Applications for access to Glacios screening only will cover a maximum of 24 grids during a one-day session.

Users’ proposals are scored in the following categories: (i) Aims & Impact; (ii) Feasibility & Data; (iii) Proposed Experiments; (iv) Goals & Expectations; (v) Expertise & Resources. The URC will score these aspects on a scale of 1-5 and also have the option to provide additional comments.

A request for access proposal will expire in three (3) cycles or when the requested amount of time recommended by peer review has been used, whichever comes first. General user projects or applications will expire in two (2) years. After that point users will have to submit a new project to submit an additional request for access applications/proposals against.

The content of the proposal will be kept confidential by the reviewer or relevant committees. A user may specify individuals that pose a potential conflict and exclude them from the external review committee.

Categories for review

The user review committee (URC) will score with respect to five (5) different categories.
(i) Aims & Impact: The specific objectives of your project. Include the scientific and technological importance of your project.
(ii) Feasibility & Data: Information and preliminary data for the samples associated with this proposal that impact feasibility of cryo-EM studies.
(iii) Proposed Experiments: The work to be conducted at the national center during the awarded project period.
(iv) Goals & Expectations: The goals for the project.
(v) Expertise & Resources: The team’s expertise in CryoEM sample preparation, microscope operation, and data interpretation, as well as the available cryoEM and/or computational resources that your team has access to.

Note: Geographical diversity, need for access by under-served or under-represented institutions, the extent of requested support, and other options available to the users or the trainees, will be taken into account in setting priorities.

These scores will be combined and averaged for a final proposal score from 1 (excellent) to 5 (poor).

Possible scores

Scores are on a scale from 1 (excellent) to 5 (poor).

Score Title Description
1 Excellent Highly innovative research of great scientific or technological importance. Access to NCCAT is integral to the success of the work.
2 Good High quality research with the potential for making an important contribution to a specific field, scientific discipline, or technical development project. Use of NCCAT resources is important to a successful outcome of the work.
3 Satisfactory Interesting research likely to produce results or incremental technological advances. The work will benefit from access to NCCAT.
4 Needs improvement Research may not significantly impact a specific field, scientific discipline, or technological area. Proposed work would also be able to be completed in other facilities including the home institution of the user.
5 Poor / Unsatisfactory Not well-planned or not feasible. The need for use of a national center is not clear.
NR No Review Insufficient information to base a review.
Note: Scored proposals that have not been assigned time will automatically be forwarded to the next cycle.


Once a project is selected, a pre-award meeting will take place to discuss the logistics of the services covered under the GPS application. Afterward the NCCAT User Office will coordinate scheduling for a 3-4 day visit to the center. Follow-up meetings will also cover safety orientation and any administrative tasks that need to be completed ahead of clearing users to come on-site to do work in the facility. During their visit, an NCCAT scientist will work closely with the user to:

  1. Prepare their samples for cryo-EM, 
  2. Vitrify samples on cryo-EM grids, 
  3. Obtain preliminary images to evaluate their samples for suitability for high resolution cryo-EM, and
  4. Iteratively optimize sample and grid preparation as needed. 

At the end of the visit, there will be a debrief meeting with the user, and an end-of-session user survey to obtain feedback on the quality of services and how to improve services.