Assembly and trafficking of human small conductance Ca2+-activated K+ channel SK3 are governed by different molecular domains.
Intracellular trafficking is an important event in the control of type and number of ion channels expressed on the cell surface. In this study, we have identified molecular domains involved in assembly and trafficking of the human small conductance Ca2+-activated K+ channel SK3. Deletion of the N-terminus, the C-terminus, or the calmodulin-binding domain (CaMBD) led to retention of SK3 channels in the endoplasmic reticulum. Presence of the CaMBD allowed trafficking to the Golgi complex, and sequences downstream were required for efficient transport to the plasma membrane, suggesting several steps in the control of SK3 forward trafficking. Co-immunoprecipitation studies demonstrated that SK3 subunits lacking the N-terminus, the CaMBD, or the distal C-terminus, but not the entire C-terminus, were able to oligomerize with wild-type SK3 subunits. Thus, these two C-terminal regions of SK3 seem to contribute to assembly and trafficking of channels whereas the N-terminus is necessary for trafficking but not sufficient for oligomerization.
Roncarati
Renza
R
Department of Medicine and Public Health, Section of Pharmacology, University of Verona, 37134 Verona, Italy. rroncarati@sienabiotech.it
Decimo
Ilaria
I
Fumagalli
Guido
G
D000595:Amino Acid Sequence; D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D004705:Endocytosis / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016716:PC12 Cells; D024681:Potassium Channels, Calcium-Activated / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051640:Small-Conductance Calcium-Activated Potassium Channels
C406328:KCNN3 protein, human; C496901:Kcnn3 protein, rat; D024681:Potassium Channels, Calcium-Activated; D011993:Recombinant Fusion Proteins; D051640:Small-Conductance Calcium-Activated Potassium Channels