Target protein not detected in IP despite using sufficient antibody and confirmed protein expression. Antibody may fail to recognize target due to protein denaturation or improper folding.
Common Causes
1Denaturing lysis buffer used with antibody that only recognizes native protein epitopes
2Non-denaturing lysis buffer used when antibody requires denatured protein for recognition
3Lysis buffer contains detergents or agents that disrupt antibody-antigen binding
4Inappropriate buffer composition causes protein aggregation or precipitation
Solutions
1Check antibody datasheet for recommended applications: IP typically requires antibodies that recognize native proteins
2Use non-denaturing lysis buffer (e.g., 50 mM Tris-HCl pH 7.4, 150 mM NaCl, 1% Triton X-100, protease inhibitors) for native IP
3Avoid strong ionic detergents (SDS >0.1%, sarkosyl) or high urea concentrations that denature proteins
4Verify lysis buffer compatibility with antibody isotype and adjust detergent type/concentration accordingly