Abstract
Thrombospondin-related anonymous protein (TRAP) family members participate in attachment and invasion of host cells by apicomplexan parasites. A TRAP homologue in Neospora caninum strain Nc-1 (NcMIC2) was cloned, sequenced and found to be 61% identical (75% similar) at the amino acid level to Toxoplasma gondii MIC2 (TgMIC2). Similar to TgMIC2, the predicted amino acid sequence of NcMIC2 contains one integrin-like domain (I or A domain), five thrombospondin (TSP) repeats, a putative transmembrane spanning region and intracellular C-terminus, and was localized to micronemes by cryo-immunoelectron microscopy. The secretion of NcMIC2 was temperature dependent and was induced at or above 25°C. The secreted form of NcMIC2 released into the medium was found to be proteolytically processed such that it lacked the C-terminal domain. Secretion of NcMIC2 was regulated by calcium, since several agents which raise intracellular calcium levels were shown to promote NcMIC2 secretion and chelation of [Ca2+](i) abrogated release. As a member of the growing family of apicomplexan TRAP proteins, NcMIC2 may play an important role in attachment and invasion by N. caninum into host cells. (C) 2000 Elsevier Science B.V.
| Original language | English |
|---|---|
| Pages (from-to) | 33-43 |
| Number of pages | 11 |
| Journal | Molecular and Biochemical Parasitology |
| Volume | 107 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 15 2000 |
Bibliographical note
Funding Information:We thank Dr Joshua Sanes for providing monoclonal antibody clone 40-1a to β-Gal, Olivia K. Giddings for cell culture assistance, and Marilyn Levy for expert electron microscopy. JLL is partially supported by NIH training grant AI07172-19 to Washington University School of Medicine, with additional support provided by USDA grant 97-35203-4770 (LDS).
Keywords
- Adhesion
- Apicomplexa
- I domain
- Microneme
- Secretion
- Thrombospondin
ASJC Scopus subject areas
- Parasitology
- Molecular Biology