Abstract:
:The mechanism of phosphosylation and dephosphorylation of spectrin from human erythrocyte membranes has been examined under closely physiological conditions. The results support the hypothesis that spectrin is an autophosphorylating and dephosphorylating system. (i) Extraction from ghosts of up to 85% of the kinase (casein kinase) suggested to catalyze the reaction [see Fairbanks, G., Avruch, J., Dino, E. J. & Patel, V. P. (1978) J. Supramol. Struct. 9, 97--112] only slightly reduced spectrin component 2 phosphorylation and did not affect ATP-induced changes in the ghosts' shapes. (ii) A spectrin--actin complex isolated from endocytotic inside-out vesicles under hyperteonic conditions contained virtually no casein kinase activity and still exhibited a largely intact phosphorylation machinery. (iii) Photoaffinity labeling experiments indicated that spectrin component 2 fulfills the necessary prerequisite of the hypothesis--i.e., it contains its own ATP-binding site. (iv) Under various conditions, spectrin phosphorylation and dephospohrylation seem to be tightly coupled. The implications of these findings for the understanding of spectrin function and the maintenance of erythrocyte shape are discussed.
journal_name
Proc Natl Acad Sci U S Aauthors
Imhof BA,Acha-Orbea HJ,Libermann TA,Reber BF,Lanz JH,Winterhalter KH,Birchmeier Wdoi
10.1073/pnas.77.6.3264subject
Has Abstractpub_date
1980-06-01 00:00:00pages
3264-8issue
6eissn
0027-8424issn
1091-6490journal_volume
77pub_type
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