Nuclear localization signal and protein context both mediate importin alpha specificity of nuclear import substrates.

The "classical" nuclear protein import pathway depends on importin alpha and importin beta. Importin alpha binds nuclear localization signal (NLS)-bearing proteins and functions as an adapter to access the importin beta-dependent import pathway. In humans, only one importin beta is known to interact with importin alpha, while six alpha importins have been described.

In vivo analysis of importin alpha proteins reveals cellular proliferation inhibition and substrate specificity.

The "classical" nuclear import pathway depends on importins alpha and beta. Humans have only one importin beta, while six alpha importins have been described. Whether or not distinct alpha importins are essential for specific import pathways in living human cells is unclear.

AMP-activated protein kinase-regulated phosphorylation and acetylation of importin alpha1: involvement in the nuclear import of RNA-binding protein HuR.

Nuclear import of HuR, a shuttling RNA-binding protein, is associated with reduced stability of its target mRNAs. Increased function of the AMP-activated protein kinase (AMPK), an enzyme involved in responding to metabolic stress, was recently shown to reduce the cytoplasmic levels of HuR. Here, we provide evidence that importin alpha1, an adaptor protein involved in nuclear import, contributes to the nuclear import of HuR through two AMPK-modulated mechanisms.

Angiotensin II type 1 receptor expression in human coronary arteries with variable degrees of atherosclerosis.

Autopsy specimens of human coronary arteries were collected from 65 men and women ranging in age from 40-76 years of age. We made 209 coronary artery sections, which were graded in terms of severity of atherosclerosis by means of the Stary classification. Sections were stained using an antibody directed against the angiotensin II type 1 (AT1) receptor.

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.