An immunoreactive form of erythrocyte protein 4.9 is present in non-erythroid cells.
Using immunoblots and an affinity-purified antibody prepared against human erythrocyte protein 4.9, we have demonstrated and quantified the presence of an immunoreactive form of this protein in avian and bovine brain and lens tissues, avian heart, as well as in human platelets and mammalian, avian, piscine, and amphibian erythrocytes. Both the 48 kDa and the 52 kDa variants were observed in human erythrocytes, whereas 50 kDa and 54 kDa immunoreactive forms were observed in human platelets. As reported for erythroid protein 4.9, platelet protein 4.9 was phosphorylated in response to treatment with phorbol ester. Bovine brain showed five cross-reactive polypeptides in the 47 to 52 kDa range while avian brain and avian and bovine lens exhibited predominantly a 49-kDa band. Cross-reactivity was not observed in a number of cell lines and tissues including leukocytes, liver, kidney, pancreas, and skeletal muscle. Immunofluorescence indicated that protein 4.9 was present in cortical fiber cells of avian lens and in neurons of avian cerebrum.
Faquin
W C
WC
Department of Cellular and Developmental Biology, Harvard University, Cambridge, MA 02138.
Husain
A
A
Hung
J
J
Branton
D
D
D000818:Animals; D001798:Blood Proteins / Q000032:analysis*; D002417:Cattle; D002645:Chickens; D003599:Cytoskeleton / Q000648:ultrastructure*; D004910:Erythrocyte Membrane / Q000032:analysis; D005455:Fluorescent Antibody Technique; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis*; D008840:Microfilament Proteins; D008970:Molecular Weight; D009928:Organ Specificity; D010750:Phosphoproteins; D013045:Species Specificity
D001798:Blood Proteins; C044805:DMTN protein, human; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins