Evidence of a laminin binding protein on the surface of Leishmania donovani

Abstract

Both the promastigote and amastigote forms of the intracellular parasite, Leishmania donovani bind the basement membrane glycoprotein laminin with high affinity (Kd = 3.56 x 10(-9) M and 3.98 x 10(-9) M respectively) with approximately 9000 and approximately 800 sites per cell. Bound laminin was identified by direct autoradiography and the binding protein through analysis of the parasite extract by SDS-PAGE and immunoblotting. A major component of 67 kDa was detected. The same protein was obtained when parasite outer membrane proteins were adsorbed to laminin-sepharose affinity matrix and subsequently eluted with SDS. The binding affinity of the isolated receptor was similar to that of the whole cells. Such a receptor isolated in Leishmania for the first time, may function as one of the bridging molecules for extracellular matrix recognition.