A Golgi-associated protein 4.1B variant is required for assimilation of proteins in the membrane.
The archetypal membrane skeleton is that of the erythrocyte, consisting predominantly of spectrin, actin, ankyrin R and protein 4.1R. The presence in the Golgi of a membrane skeleton with a similar structure has been inferred, based on the identification of Golgi-associated spectrin and ankyrin. It has long been assumed that a Golgi-specific protein 4.1 must also exist, but it has not previously been found. We demonstrate here that a hitherto unknown form of protein 4.1, a 200 kDa 4.1B, is associated with the Golgi of Madin-Darby canine kidney (MDCK) and human bronchial epithelial (HBE) cells. This 4.1B variant behaves like a Golgi marker after treatment with Brefeldin A and during mitosis. Depletion of the protein in HBE cells by siRNA resulted in disruption of the Golgi structure and failure of Na(+)/K(+)-ATPase, ZO-1 and ZO-2 to migrate to the membrane. Thus, this newly identified Golgi-specific protein 4.1 appears to have an essential role in maintaining the structure of the Golgi and in assembly of a subset of membrane proteins.
Kang
Qiaozhen
Q
Red Cell Physiology Laboratory, New York Blood Center, New York, NY 10065, USA.
Wang
Ting
T
Zhang
Huizheng
H
Mohandas
Narla
N
An
Xiuli
X
D000818:Animals; D000906:Antibodies; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D004285:Dogs; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008840:Microfilament Proteins; D008970:Molecular Weight; D010750:Phosphoproteins / Q000378:metabolism; D020033:Protein Isoforms; D021381:Protein Transport; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
D000906:Antibodies; C116887:EPB41L3 protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; C569042:TJP1 protein, human; C569046:TJP2 protein, human; D025521:Tumor Suppressor Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; D020126:Brefeldin A; D000254:Sodium-Potassium-Exchanging ATPase