Investigations of tetraspanin functions using large extracellular loops

This thesis describes our characterization of a specific tetraspanin domain: the large extracellular loop (LEL). Tetraspanins are involved in cellular migration, adhesion, and metastasis, sperm-egg fusion, and viral infectivity. The large extracellular loop domain is the major extracellular domain of tetraspanins and the binding of a monoclonal antibody against the tetraspanin CD9 serves to inhibit fertilization, consistent with the CD9-null mouse model. The first area of focus in this thesis is the characterization of the murine CD9-LEL domain. We present a methodology to express and purify the mCD9-LEL to homogeneity. Biophysical characterization of the mCD9-LEL protein reveals that it is an autonomously folding, [alpha]-helical dimer. Mutagenesis over much of the mCD9-LEL protein reveals that it is composed of two subdomains: a dimerization subdomain and a variable subdomain proposed to mediate heterotypic interactions. These results suggest both a means for exploring endogenous tetraspanins functions and a mechanism by which tetraspanins may oligomerize. Surprisingly, we were not able to detect oligomerization of the intact CD9 molecule, in discordance with our biophysical data on the mCD9-LEL.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Liu, Christopher C

Advisor dc:contributor.advisor

• Peter S. Kim and Richard O. Hynes.

• Biology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/33751
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/33751

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33751