Single amino acid substitutions in one Ca2+ binding site of uvomorulin abolish the adhesive function |
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Authors: | M Ozawa J Engel R Kemler |
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Institution: | Max-Planck Institut für Immunobiologie, Molekulare Embryologie, Freiburg, Federal Republic of Germany. |
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Abstract: | We show that a synthetic peptide corresponding to the sequence of one putative Ca2+ binding motif of the cell adhesion molecule uvomorulin is able to complex Ca2+. This function is abolished if the first Asp in the peptide is replaced by Lys. Accordingly, we expressed in L cells mutant uvomorulin with a replacement of Asp to Lys or Ala. Mutant protein was resistant to Ca2+/trypsin under mild conditions but became susceptible at or near the site of replacement at higher concentrations, leaving the remaining Ca2+ binding domains protected. Remarkably, in cell aggregation assays both mutant uvomorulins failed to mediate cell adhesiveness, demonstrating that a single amino acid substitution in one Ca2+ binding site inactivates the adhesive function. |
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