A repetitive DNA sequence in Paramecium macronuclei is related to the beta subunit of G proteins.

AUTOR(ES)

Forney, J

RESUMO

A repeated DNA sequence has been identified in the macronucleus of several Paramecium species. In P.tetraurelia the repeat was identified in the subtelomeric region of four randomly selected telomere clones, as well as downstream of the A type variable surface protein gene. The complete sequence of the A gene linked repeat consists of 15 tandem repeats of exactly 126 nucleotides that contain an open reading frame with significant similarity to the beta subunits of trimeric G proteins. The most striking consensus feature is the amino acid sequence DX omega WD where X is any amino acid and omega is I, L, or V spaced at precise 42 amino acids intervals. This sequence and spacing are found in G-protein beta subunits and other members of this protein motif family. Analysis of the five cloned telomeric restriction fragments showed the repeats can be found in either orientation with respect to the telomere. Poly(A) RNA transcripts containing this sequence have been identified in Paramecium tetraurelia. The conserved presence of this sequence in several species of Paramecium suggests an important physiological function, and the study of this repeat may reveal information about the evolution of this common protein motif.

Documentos Relacionados

• A second form of the beta subunit of signal-transducing G proteins.
• A 102 kDa subunit of a Golgi-associated particle has homology to beta subunits of trimeric G proteins.
• Occurrence in Saccharomyces cerevisiae of a gene homologous to the cDNA coding for the alpha subunit of mammalian G proteins.
• Cloning of an intracellular receptor for protein kinase C: a homolog of the beta subunit of G proteins.
• Subunit of an alpha-interferon-responsive transcription factor is related to interferon regulatory factor and Myb families of DNA-binding proteins.