Analysis of the CD151·α3β1 Integrin and CD151·Tetraspanin Interactions by Mutagenesis

• Published in: The Journal of biological chemistry Vol. 276; no. 44; p. 41165
• Main Authors: Fedor Berditchevski, Elizabeth Gilbert, Meryn R. Griffiths, Steven Fitter, Leonie Ashman, Sonya J. Jenner
• Format: Journal Article
• Language: English
• Published: American Society for Biochemistry and Molecular Biology 02.11.2001
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M104041200

Transmembrane proteins of the tetraspanin superfamily are associated with various integrins and modulate their function. We performed mutagenesis analysis to establish structural requirements for the interaction of CD151 with the α 3 β 1 integrin and with other tetraspanins. Using a panel of CD151/CD9 chimeras and CD151 deletion mutants we show that the minimal region, which confers stable ( e.g. Triton X-100-resistant) association of the tetraspanin with α 3 β 1 , maps within the large extracellular loop (LECL) of CD151 (the amino acid sequence between residues Leu 149 and Glu 213 ). Furthermore, the substitution of 11 amino acids (residues 195–205) from this region for a corresponding sequence from CD9 LECL or point mutations of cysteines in the conserved CCG and P XX CC motifs abolish the interaction. The removal of the LECL CD151 does not affect the association of the protein with other tetraspanins ( e.g. CD9, CD81, CD63, and wild-type CD151). On the other hand, the mutation of the CCG motif selectively prevents the homotypic CD151·CD151 interaction but does not influence the association of the mutagenized CD151 with other tetraspanins. These results demonstrate the differences in structural requirements for the heterotypic and homotypic tetraspanin·tetraspanin interactions. Various deletions involving the small extracellular loop and the first three transmembrane domains prevent surface expression of the CD151 mutants but do not affect the CD151·α 3 β 1 interaction. The CD151 deletion mutants are accumulated in the endoplasmic reticulum and redirected to the lysosomes. The assembly of the CD151·α 3 β 1 complex occurs early during the integrin biosynthesis and precedes the interaction of CD151 with other tetraspanins. Collectively, these data show that the incorporation of CD151 into the “tetraspanin web” can be controlled at various levels by different regions of the protein.