Glycogen Synthetase of Bee Larvae
During the larval stage of the honeybee there is an abrupt and very large elevation of glycogen content. Homogenates from larvae of high glycogen content have an active glycogen synthetase that is associated with the particulate glycogen fraction. Although the enzyme resembles mammalian glycogen syn...
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Veröffentlicht in: | The Journal of biological chemistry 1967-05, Vol.242 (10), p.2306-2311 |
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Sprache: | eng |
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Zusammenfassung: | During the larval stage of the honeybee there is an abrupt and very large elevation of glycogen content. Homogenates from
larvae of high glycogen content have an active glycogen synthetase that is associated with the particulate glycogen fraction.
Although the enzyme resembles mammalian glycogen synthetase in many of its properties there is at least one important difference.
The enzyme bound with particulate glycogen of bee larvae, but not of mammals, is an active enzyme-substrate complex, since
high rates of glucose incorporation are observed in the absence of added soluble primer. The main factor limiting incorporation
of glucose into glycogen under the conditions of these experiments seems to be the length of outer branch chains in the primer.
When this limit is reached, incorporation stops. Addition of glucose 6-phosphate causes incorporation to resume until a higher
limit is attained. Two alternative interpretations of this effect are possible. Glucose 6-phosphate either changes the specificity
of the enzyme for primer outer chains or activates a glucose 6-phosphate-dependent form of the enzyme that can utilize longer
outer chains as effective priming units. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)95963-6 |