Abstract: The present invention describes that OTUB1 cleavage of K48 poly-ubiquitin is stimulated by a select subset of E2 enzymes, and that this stimulation is regulated by the ubiquitin-charged state of the E2 and free ubiquitin. Structural and biochemical studies of OTUB1 and UBCH5B show that the E2 stimulates binding of the polyubiquitin substrate by contacting the OTUB1 N-terminal ubiquitin-binding helix. Methods for identifying E2 enzymes which stimulate or inhibit cleavage of K48 polyubiquitin, as well as novel target compounds which modulate this interaction are provided.

Abstract: Disclosed herein is a system for facilitating charitable gift giving including a card request interface configured to provide a charitable gift card to a requestor. The charitable gift card is tagged with identification information. The computerized system further includes a server comprising a payment interface configured to accept a payment and credit a value of money corresponding to the payment to the charitable gift card, wherein the payment interface is separate from the card interface, and a charity selection interface. The charity selection interface is configured to accept information related to the identification information, receive a selection of a donee charity and an amount to be paid using the identification information, pay the donee charity the amount to be paid, and deduct the amount to be paid from the amount credited to the charitable gift card.