Calretinin and calbindin D28k have different domain organizations

Małgorzata Palczewska, Patrick Groves, Gyula Batta, Bert Heise, Jacek Kuźnicki

Research output: Article

26 Citations (Scopus)


The domain organization of calretinin (CR) was predicted to involve all six EF-hand motifs (labeled I to VI) condensed into a single domain, as characterized for calbindin D28k (Calb), the closest homolog of calretinin. Unperturbed 1H, 15N HSQC NMR spectra of a 15N-labeled calretinin fragment (CR III-VI, residues 100-271) in the presence of the unlabeled complimentary fragment (CR I-II, residues 1-100) show that these fragments do not interact. Size exclusion chromatography and affinity chromatography data support this conclusion. The HSQC spectrum of 15N-labeled CR is similar to the overlaid spectra of individual 15N-labeled CR fragments (CR I-II and CR III-VI), also suggesting that these regions do not interact within intact CR. In contrast to these observations, but in accordance with the Calb studies, we observed interactions between other CR fragments: CR I (1-60) with CR II-VI (61-271), and CR I-III (1-142) with CR IV-VI (145-271). We conclude that CR is formed from at least two independent domains consisting of CR I-II and CR III-VI. The differences in domain organization of Calb and CR may explain the specific target interaction of Calb with caspase-3. Most importantly, the comparison of CR and Calb domain organizations questions the value of homologous modeling of EF-hand proteins, and perhaps of other protein families.

Original languageEnglish
Pages (from-to)180-184
Number of pages5
JournalProtein Science
Issue number1
Publication statusPublished - jan. 1 2003

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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