MOMP is the acronym for "major outer-membrane protein", a protein with a trimeric conformation that plays a major role in the integrity (structural rigidity of the outer membrane) and antigenicity of Chlamydia, among other things.
Extraction of MOMP from Chlamydia isolates under non-denaturing conditions revealed that native MOMP trimers exhibit porin-like channel-forming activity. The pore size was estimated to be approximately 2 nm in diameter. Together with the lipopolysaccharide, the major out membrane protein (MOMP) forms the surface of the elementary body cell. Disulfide bond interactions within and between MOMP molecules and other components form high molecular weight oligomers.