Restricted tissue distribution of a 37-kD possible adherens junction protein.
A major polypeptide of M(r) 37,000 was purified from a desmosome-enriched citric acid-insoluble pellet of pig tongue epithelium. The polypeptide was solubilized from the 4-M urea-insoluble pellet with 9 M urea, and extracts were separated by carboxymethyl cellulose and gel filtration chromatography. The 37-kD protein was obtained in milligram quantities as a single band on two-dimensional gels in 30% yield after 21-fold purification from the citric acid-insoluble fraction. The protein is not glycosylated and has a pI of approximately 8.7. Although isolated from a fraction rich in desmosomes, the 37-kD protein is not a desmosomal protein. Indirect immunofluorescence analysis of frozen sections of tongue and other tissues demonstrated that antibodies raised to the 37-kD protein bound only to suprabasal cell layers at punctate regions of the periphery of the cell and was absent from most regions of epidermis, whereas antibodies to desmoplakins I and II, desmosomal proteins, bound similarly but in all epidermal layers. Immunoelectron microscopy localized the 37-kD protein to the cell periphery in regions between, but never in, desmosomes. By immunofluorescence, the 37-kD protein colocalized with actin as well as with vinculin and uvomorulin in oral tissues. Like the 37-kD protein, vinculin and uvomorulin were absent from the basal layer. Based on its appearance, localization, and solubility properties, the 37-kD protein is probably a component of adherens junctions; its restriction to suprabasal cells and exclusion from the epidermis are unique.
Chiu
M L
ML
Department of Dermatology, University of North Carolina, Chapel Hill 27514.
Jones
J C
JC
O'Keefe
E J
EJ
D000199:Actins / Q000302:isolation & purification; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015703:Antigens, CD; D015820:Cadherins / Q000302:isolation & purification; D015815:Cell Adhesion Molecules / Q000302:isolation & purification*; D003896:Desmosomes / Q000737:chemistry; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry / Q000648:ultrastructure; D006031:Glycosylation; D007365:Intercellular Junctions / Q000737:chemistry*; D007526:Isoelectric Point; D008970:Molecular Weight; D012995:Solubility; D013552:Swine; D014018:Tissue Distribution; D014059:Tongue / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure; D016596:Vinculin / Q000302:isolation & purification
D000199:Actins; D000596:Amino Acids; D015703:Antigens, CD; C050361:CDH2 protein, human; D015820:Cadherins; D015815:Cell Adhesion Molecules; D016596:Vinculin