Isolation and characterization of calreticulin oligomers

MORESCHI A.C.; DURAND E.S.; MONTICH G.G.; DECCA M.B.

Villa Carlos Paz

Congreso; XLII Reunión Anual de la Sociedad Argentina de Biofísica-SAB2013; 2013

Sociedad Argentina de Biofísica

Calreticulin (CRT) oligomerization occurs in living cells as a response to stress, and leads to an enhancement in chaperon and polypeptide binding activities of this protein. Recruitment of CRT oligomers seems to be critical for the scaffolding of stress granules in cytoplasm, a mechanism that regulates mRNA translation as a response to stress. Extended CRT oligomerization has been also proposed to act as a large platform for binding of different substrates. Here we describe a method for isolation of CRT oligomers, as well as its biophysical characterization. Circular dichroism spectroscopy was used to determine structural properties of CRT oligomers in comparison with monomeric CRT. We found that the global secondary structure of calreticulin is retained in oligomers whereas tertiary structure is partially lost. Differential scanning calorimetry showed no cooperative transition in the thermal denaturation of CRT oligomers, and a decreased thermal stability in comparison with CRT monomers. Despite the importance of CRT oligomers in expanding CRT functions, no structural characterization of CRT oligomers has yet been performed.