The present disclosure provides methods and reagents useful for analyzing protein-protein interfaces such as interfaces between a presenter protein (e.g., a member of the FKBP family, a member of the cyclophilin family, or PIN1) and a target protein. In some embodiments, the target and/or presenter proteins are intracellular proteins. In some embodiments, the target and/or presenter proteins are mammalian proteins.

The present disclosure relates to molecules capable of binding to both CD20 and PD1, as well as pharmaceutical compositions comprising such molecules and methods of use thereof.

This application relates to random polymer libraries and specific polymers that can be used, for example, in stabilizing high concentration protein compositions, such as high concentration antibody compositions.

Provided is the use of a polypeptide with calcium indicator activity which comprises an amino acid sequence represented by SEQ ID NO. 1, or an amino acid sequence which has at least 80% sequence identity thereto, for identifying transmembrane pore formation capability of a target polypeptide, especially an insecticidal protein, in a cellular assay.

Methods and compositions for multiplexed protein-protein interaction profiling (e.g., immunoprofiling), based on nucleic acid tagging of polypeptides (e.g., by RNA display) are described. In some embodiments the described compositions and methods utilize a library of prey polypeptide targets linked to prey RNAs encoding them, and a population of bait polypeptides, e.g., a mixture of antibodies, that bind to one or more of the prey polypeptide targets and are used to isolate and identify the bound prey polypeptide targets by amplification of their associated prey RNAs and sequencing of the corresponding cDNAs. In other embodiments the prey polypeptide targets are linked to DNA Bar Codes, which serve as unique identifiers of the tagged polypeptide.

The present invention relates, inter alia, to polyspecificity reagents, methods of making the same, and methods of using the same in, inter alia, the selection, screening, enrichment, and identification of non-polyspecific, and thus developable, polypeptides.

The present invention resides in the discovery that the presence of anti-PF4 antibody in the PF4-integrin complex promotes platelet aggregation and subsequently thrombocytopenia. PF4 mutants incapable of binding integrin are also disclosed as inhibitors of the PF4-integrin complex and thus useful therapeutic agents against thrombocytopenia. Therefore, this invention provides methods for diagnosis and treatment of thrombocytopenia.

Trypsin/trypsin-like proteases have been reported to be facilitating SARS-COV-2 entry into host cells. Spike has protease cleavage sites between the S1 and S2 domains. Cleavage property of proteases can be used to design drug screening assays meant for screening antiviral candidates against spike cleavage. In the claimed invention we have developed a proof-of-concept assay system for screening drugs against proteases which cleave spike between S1 and S2. We designed a fusion substrate protein containing a reporter protein, the protease cleavage site between S1 and S2 and a cellulose binding domain. The substrate protein can be immobilized on cellulose due to the presence of cellulose binding domain (CBD). When proteases cleave the substrate. CBD remains bound to cellulose and the reporter protein is dislodged. The released reporter can be used as read out of protease activity.

Disclosed in the present invention is a method for detecting a protein having changes in an energy state, and affinity of a ligand to a protein. Specifically, after the energy state of a protein changes, its tolerance to proteolytic cleavage destruction changes. The structure of the protein in a low-energy state is also destroyed under a non-denaturation condition by using a large amount of enzymes, and small peptide fragments, which have molecular weight of less than 5 KDa and can be directly used for bottom-top mass spectrometry analysis, are directly generated. The method has extremely high sensitivity. Quantitative proteomics is used to find enzyme cleavage differential peptide fragments, and proteins to which the differential peptide fragments belong and the positions in the proteins are analyzed, so that a protein having changes in an energy state, and a change region can be determined in the whole proteome range. If the energy state of the protein changes due to addition of a ligand, the method can determine a binding protein and a binding region of the ligand; and the output of a quantitative result on the peptide fragment level further enables the method to determine the local affinity of binding of the ligand to the protein.

This system presents a comprehensive approach for detecting protein-protein interactions and exploring protein structures. It encompasses various components, including a receptacle for receiving cross-linked precursor peptides, a mass spectrometer for generating MS1 and MS2 spectra, and modules for precursor mass refinement, MS2 spectrum scoring, protein score database construction, and feedback mechanism processing. Through the integration of these elements, the system facilitates the identification of peptide interactions and protein structures, leveraging a cross-linking dataset obtained from proteins cross-linked with cleavable or non-cleavable crosslinking reagents.