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  • Proceedings of the National Academy of Sciences  (2)
  • 2000-2004  (2)
  • 1
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2003
    In:  Proceedings of the National Academy of Sciences Vol. 100, No. 22 ( 2003-10-28), p. 12660-12665
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 100, No. 22 ( 2003-10-28), p. 12660-12665
    Abstract: Pancreatic α and β cells are derived from the same progenitors but play opposing roles in the control of glucose homeostasis. Disturbances in their function are associated with diabetes mellitus. To identify many of the proteins that define their unique pathways of differentiation and functional features, we have analyzed patterns of gene expression in αTC1.6 vs. MIN6 cell lines by using oligonucleotide microarrays. Approximately 9–10% of 〉 11,000 transcripts examined showed significant differences between the two cell types. Of 〉 700 known transcripts enriched in either cell type, transcription factors and their regulators (TFR) was one of the most significantly different categories. Ninety-six members of the basic zipper, basic helix–loop–helix, homeodomain, zinc finger, high mobility group, and other transcription factor families were enriched in α cells; in contrast, homeodomain proteins accounted for 51% of a total of 45 TFRs enriched in β cells. Our analysis thus highlights fundamental differences in expression of TFR subtypes within these functionally distinct islet cell types. Interestingly, the α cells appear to express a large proportion of factors associated with progenitor or stem-type cells, perhaps reflecting their earlier appearance during pancreatic development. The implications of these findings for a better understanding of α and β cell dysfunction in diabetes mellitus are also considered.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2003
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 99, No. 2 ( 2002-01-22), p. 1035-1040
    Abstract: The Kv4 A-type potassium currents contribute to controlling the frequency of slow repetitive firing and back-propagation of action potentials in neurons and shape the action potential in heart. Kv4 currents exhibit rapid activation and inactivation and are specifically modulated by K-channel interacting proteins (KChIPs). Here we report the discovery and functional characterization of a modular K-channel inactivation suppressor (KIS) domain located in the first 34 aa of an additional KChIP (KChIP4a). Coexpression of KChIP4a with Kv4 α-subunits abolishes fast inactivation of the Kv4 currents in various cell types, including cerebellar granule neurons. Kinetic analysis shows that the KIS domain delays Kv4.3 opening, but once the channel is open, it disrupts rapid inactivation and slows Kv4.3 closing. Accordingly, KChIP4a increases the open probability of single Kv4.3 channels. The net effects of KChIP4a and KChIP1–3 on Kv4 gating are quite different. When both KChIP4a and KChIP1 are present, the Kv4.3 current shows mixed inactivation profiles dependent on KChIP4a/KChIP1 ratios. The KIS domain effectively converts the A-type Kv4 current to a slowly inactivating delayed rectifier-type potassium current. This conversion is opposite to that mediated by the Kv1-specific “ball” domain of the Kvβ1 subunit. Together, these results demonstrate that specific auxiliary subunits with distinct functions actively modulate gating of potassium channels that govern membrane excitability.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    RVK:
    RVK:
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2002
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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