Carcinoembryonic antigen cell adhesion molecule 1 (CEACAM1) structure and uses thereof in drug identification and screening

A method for screening and selecting a candidate substance for sufficient binding and/or that inhibits binding to a CEACAM1 or a structurally related CEA family member molecule comprising:

• preparing a soluble CEACAM1antigen comprising a functional binding domain, D1, having a protruding, convoluted CC′ loop amino acid sequence of K G E R V D G N R Q a C-terminal domain, D4, having an elongated CD loop, and a flexible linker connecting D1 to D4, to provide a target molecule;
• preparing a control sample comprising the target molecule and a monoclonal antibody or other antibody-like functionally equivalent molecules having specific binding affinity for the CC′ loop or that competes for binding to serial CC′ loop, and preparing a test sample comprising the target molecule and a candidate substance;
• incubating the control sample and the test sample for a period of time and under appropriate conditions to permit binding to the target molecule in the control sample;
• and
• comparing the amount of bound target molecule in the control sample to the amount of candidate agent bound to the target molecule in the test sample,
• wherein a candidate agent having at least 40% the amount of bound candidate agent to target molecule compared to the amount of bound target molecule in the control sample is selected as having sufficient binding/inhibiting activity.