The major surface protein (MSP1) of the cattle pathogen Anaplasma is a heterodimer comprised of MSP1a and MSP1b. This family is the MSP1b chain. There MSP1 proteins are putative adhesins for bovine erythrocytes.

1: Differential adhesion of major surface proteins 1a and 1b of the ehrlichial cattle pathogen Anaplasma marginale to bovine erythrocytes and tick cells. de la Fuente J, Garcia-Garcia JC, Blouin EF, Kocan KM; Int J Parasitol 2001;31:145-153. PMID:11239934