An ion-current mutant of Paramecium tetraurelia with defects in the primary structure and post-translational N-methylation of calmodulin
My work on pantophobiac A{sup 2} (pntA{sup 2}), a behavioral mutant of Paramecium tetraurelia, suggest that the Ca{sup ++}-binding protein calmodulin (CaM), and post-translation N-methylation of CaM, are important for Ca{sup ++}-related ion-current function. Calmodulin from wild-type Paramecium has two sites of lysine-N-methylation. Both of these sites are almost fully methylated in vivo; thus wild-type calmodulin is a poor substrate for N-methylation in vitro. In contrast, pntA/{sup 2} CaM can be heavily N-methylated in vitro, suggesting that the mutant calmodulin is under-methylated in vivo. Amino-acid composition analysis showed that CaM lysine 115 is undermethylated in pntA{sup 2}. Once pntA{sup 2} CaM is N-methylated, the (methyl-{sup 3}H) group does not turn over in either wild-type or pntA{sup 2} cytoplasmic fractions. The methylating enzymes in pntA{sup 2} high-speed supernatant fractions are active, but may be less robust than those of the wild type, suggesting a possible control of these enzymes by CaM.
- Research Organization:
- Wisconsin Univ., Madison, WI (USA)
- OSTI ID:
- 7244628
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALMODULIN
METHYLATION
MOLECULAR STRUCTURE
AMINO ACID SEQUENCE
MUTANTS
PARAMECIUM
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
CHEMICAL REACTIONS
CILIATA
HYDROGEN COMPOUNDS
INVERTEBRATES
ISOTOPE APPLICATIONS
MICROORGANISMS
ORGANIC COMPOUNDS
PROTEINS
PROTOZOA
550201* - Biochemistry- Tracer Techniques