This symmetric design puzzle has C2 symmetry, with two symmetric chains. The H-bond Network Objective encourages players to bury H-bond Networks at the interface between the two chains. We've doubled the H-bond Network bonus, but we'd like players to focus on building networks deep in the core of the protein complex. There are a couple other bonuses in effect; see the puzzle comments for details. The Baker Lab will run folding predictions on your solutions for this puzzle, and those that perform well will be synthesized in the lab. Remember, you can use the Upload for Scientists button for up to 5 designs that you want us to look at, even if they are not the best-scoring solutions!

Design a protein to stabilize the CR2-binding helices! Complement receptor 2 (CR2) is a protein found on the surface of human B-cells, which respond to viruses and other pathogens found in the body. When the CR2 protein is activated, these immune cells become especially sensitive. We want to design a protein that can bind to CR2 and help trigger a strong immune response. Such a protein could boost the effectiveness of vaccines. The starting structure contains two helices from a natural protein, which is known to bind CR2 but is not very stable. We're asking Foldit players to design a protein to stabilize these two helices in their starting orientation. The side chains involved in CR2 binding are frozen; Foldit players should avoid building around these residues, which need to remain accessible for CR2 binding. Some protein design Objectives are in effect; see the puzzle comments for details.

This protein is another part of the same protein complex with multiple subunits from Puzzle 1554, Puzzle 1588, and Puzzle 1598 which has been the target of cryo-EM experiments. Like in Puzzle 1598, we are giving you 2 weeks and an extended chain to start with, so good luck!

This symmetric design puzzle has C2 symmetry, with two symmetric chains. The H-bond Network Bonus encourages players to bury H-bond networks at the interface between the two chains. We've doubled the H-bond network bonus, but we'd like players to focus on building networks deep in the core of the protein complex. There are a couple other bonuses in effect; see the puzzle comments for details. The Baker Lab will run folding predictions on your solutions for this puzzle, and those that perform well will be synthesized in the lab. Remember, you can use the Upload for Scientists button for up to 5 designs that you want us to look at, even if they are not the best-scoring solutions!

This is a throwback puzzle to the early days of Foldit. This small domain is part of a larger protein found at high concentrations of the lens of the eye; historically, this protein was purified from the eyes of B. taurus for research. The protein is modeled here in reduced state, so no disulfides are expected to form. We are revisiting old Foldit puzzles so we can see how useful the recent additions to the game have been.

This symmetric design puzzle has C2 symmetry, with two symmetric chains. There is no H-bond Network Objective in this puzzle, so the interface can be completely nonpolar (orange sidechains). There are no helix restrictions, but all loops must match one of the Ideal Loop Building Blocks found in the Blueprint tool. See the puzzle comments for Objective details. The Baker Lab will run folding predictions on your solutions for this puzzle, and those that perform well will be synthesized in the lab. Remember, you can use the Upload for Scientists button for up to 5 designs that you want us to look at, even if they are not the best-scoring solutions!

This is a throwback puzzle to the early days of Foldit. This protein is secreted at the site of inflammation, recruiting monocytes and T cells to help fight an infection. This protein contains four cysteine residues that oxidize to form two disulfide bonds. We are revisiting old Foldit puzzles so we can see how useful the recent additions to the game have been.

The structure of this protein is still unknown. Secondary structure predictions (from PSIPRED) are marked on the starting structure, and provide clues about where the protein might form helices and sheets!

This symmetric design puzzle has C2 symmetry, with two symmetric chains. There is no H-bond Network Objective in this puzzle, so the interface can be completely nonpolar (orange sidechains). However, there other stringent objectives in effect: solutions may have no more than 50% of residues in helices, and all loops must match one of the Ideal Loop Building Blocks found in the Blueprint tool. See the puzzle comments for Objective details. The Baker Lab will run folding predictions on your solutions for this puzzle, and those that perform well will be synthesized in the lab. Remember, you can use the Upload for Scientists button for up to 5 designs that you want us to look at, even if they are not the best-scoring solutions!

This is a throwback puzzle to the early days of Foldit. This small peptide is part of a larger protein that helps to regulate cell division, and is very important in early embryonic development. The protein is modeled here as in a reduced environment, so no disulfide bonds are expected to form. We are revisiting old Foldit puzzles so we can see how useful the recent additions to the game have been.