Smoothelin contains a novel actin cytoskeleton localization sequence with similarity to troponin T.
Smoothelin, a cytoskeletal protein, exists in a large isoform specifically expressed in vascular smooth muscle cells, and a small visceral isoform generated by a downstream transcriptional start site. Using fusions to the green fluorescent protein, we could show that both smoothelin isoforms are localized at actin containing filaments and mapped two domains that are each sufficient for localization at the actin cytoskeleton. The first domain is located in the vascular-specific, N-terminal half of smoothelin and the second in the common, C-terminal half. The second domain shares clear sequence similarity with a domain of troponin T involved in actin filament association. These results suggest that the tissue-specific expression of smoothelin isoforms might contribute to the different contractile properties of smooth muscle cells.
Quensel
Christina
C
Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany.
Krämer
Jochen
J
Cardoso
Maria Cristina
MC
Leonhardt
Heinrich
H
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002645:Chickens; D016384:Consensus Sequence; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D020107:Troponin T / Q000737:chemistry / Q000378:metabolism*
D000199:Actins; D003598:Cytoskeletal Proteins; D008164:Luminescent Proteins; D009124:Muscle Proteins; C491050:Smtn protein, mouse; D020107:Troponin T; D049452:Green Fluorescent Proteins