Band 3 tyrosine kinase in avian erythrocyte plasma membrane is immunologically related to pp60c-src

Abstract

We have identified in the plasma membrane of the chicken erythrocyte a 60-kDa tyrosine-specific protein kinase immunologically related to the transforming protein pp60v-src of Rous sarcoma virus. The erythrocyte protein kinase phosphorylated heavy chains of tumor-bearing rabbit (TBR) antibodies reactive with pp60c-src at tyrosine in immune complex protein kinase assays. The kinase was identified as a 60-kDa protein by [35S]methionine labeling of erythrocytes and by autophosphorylation in immune complexes. The kinase migrated on two-dimensional gel electrophoresis with an apparent pI and molecular mass similar to pp60c-src. A plasma membrane-enriched fraction isolated from chicken red cells contained the majority of the kinase activity. The kinase was solubilized from the plasma membrane by the detergents 0.5% (wt/vol) Na-deoxycholate and 1% (vol/vol) Nonidet P-40. One molar NaCl was much less effective, indicating a strong association of the kinase with the plasma membrane. Incubation of the plasma membrane fraction with [32P]ATP resulted in tyrosine phosphorylation of the anion transport protein band 3. Band 3 phosphorylation was blocked by TBR antibodies, indicating that the kinase recognized by pp60c-src antibodies was responsible for band 3 phosphorylation. These results demonstrate that the avian erythrocyte plasma membrane contains a tightly bound tyrosine-specific protein kinase identical or closely related to pp60c-src and that this kinase is responsible for band 3 phosphorylation in vitro.