Intestinal alkaline phosphatase of the fishCyprinus carpio: Regional distribution and membrane association

Autor: Julieta Villanueva, Roberto Vanacore, Oscar Goicoechea, Rodolfo Amthauer
Rok vydání: 1997
Předmět:
Zdroj: The Journal of Experimental Zoology. 279:347-355
ISSN: 1097-010X
0022-104X
DOI: 10.1002/(sici)1097-010x(19971101)279:4<347::aid-jez4>3.0.co;2-o
Popis: The distribution of alkaline phosphatase along the carp intestine and also its association to the enterocyte membrane have been studied in order to correlate them with the morphological features and functional specialization of the different intestine portions. The intes- tine was sectioned in seven segments and from each segment a butanol extract of intestinal alka- line phosphatase (IAP) was prepared. The enzyme activity, when expressed as a function of the mucosa or protein content of each segment showed a clear proximo-distal gradient. In addition, IAP was recovered in the precipitate after centrifugation of the homogenate, along the intestine, indicating that it is membrane associated protein. Also, when brush border membranes (BBM) were isolated, IAP was enriched 10-fold. Butanol extracted IAP from all segments exhibited three bands of activity when separated in PAGE-Triton X-100. The slowest migrating band showed a hydrophobic character as it was retained in a phenyl-Sepharose CL-4B column, whereas the other bands represent hydrophilic IAP found in the flow through of the column. Butanol extracted IAP from BBM rendered only one band with hydrophobic character in PAGE-Triton X-100, which could be converted to hydrophilic forms when incubated with phosphatidyl-inositol phospholipase C. These results clearly demonstrate, that in carp as well as in all other species studied, IAP is anchored to the membrane via a glycosyl-phosphatidylinositol. The high IAP content found in the first segment is consistent with the function of dephosphorylation of nutritional compounds pro- posed in higher vertebrates. The involvement of IAP in other physiological roles such as lipid absorption or protein internalization cannot be ruled out. J. Exp. Zool. 279:347-355, 1997.
Databáze: OpenAIRE
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