CpABC, a Cryptosporidium parvum ATP-binding cassette protein at the host-parasite boundary in intracellular stages

The intracellular parasite Cryptosporidium parvum develops inside a vacuole at the apex of its epithelial host cell. The developing parasite is separa ted from the host cell cytoplasm by a zone of attachment that consists of a n extensively folded membranous structure known as the feeder organelle, It has been proposed that the feeder organelle is the site of regulation of t ransport of nutrients and drugs into the parasite. In this report, we local ize an approximate to 200-kDa integral membrane protein, CpABC, from Crypto sporidium parvum to the host-parasite boundary, possibly the feeder organel le, The predicted amino acid sequence of CpABC has significant structural s imilarity with the cystic fibrosis conductance regulator and the multidrug resistance protein subfamily of ATP-binding cassette proteins, This is an e xample of a parasite-encoded transport protein localized at the parasite-ho st interface of an intracellular protozoan.