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Multiple forms of glucagon and somatostatin isolated from the intestine of the southern-hemisphere lamprey Geotria australis.

Abstract：

:Current views on Agnathan phylogeny favor the hypothesis that the genera of holarctic lampreys belong to a single family (Petromyzontidae) and form an interrelated progression in which Petromyzon is near to Ichthomyzon at the base of the phylogenetic tree and Lampetra is the most derived. A stock similar to that of contemporary Ichthomyzon is considered to have given rise to the southern hemisphere lamprey Geotria australis, the sole member of the Geotriidae. In the present study, two molecular forms of glucagon were isolated from an extract of G. australis intestine that differed in structure by six amino acid residues. One form shows two amino acid substitutions (Leu14 --> Met and Ala29 --> Ser) compared with the single molecular form of glucagon isolated from the sea lamprey Petromyzon marinus and the second form shows three substitutions (Asp15 --> Glu, Ser16 --> Ala, Ile24 --> Thr) compared with the single glucagon isolated from the river lamprey Lampetra fluviatilis. As Petromyzon and Lampetra glucagons differ by six amino acid residues, the data suggest that a duplication of the glucagon gene occurred prior to or early in lamprey evolution. Although both genes are strongly expressed in G. australis, the expression of one gene predominates in P. marinus while that of the other gene predominates in L. fluviatilis. Previous work has shown that, in the islet organ of G. australis, preprosomatostatin is processed almost exclusively to somatostatin-33. However, the present study demonstrates that somatostatin-14 is the major molecular form in G. australis intestine with somatostatin-33 present only as a minor component. This result demonstrates a tissue-dependent pathway of posttranslational processing of preprosomatostatin in the Geotria enteropancreatic system.

journal_name

Gen Comp Endocrinol

journal_title

General and comparative endocrinology

authors

Wang Y,Nielsen PF,Youson JH,Potter IC,Conlon JM

doi

10.1006/gcen.1998.7203

keywords:

subject

Has Abstract

pub_date

1999-02-01 00:00:00

pages

274-82

issue

eissn

0016-6480

issn

1095-6840

pii

S0016-6480(98)97203-3

journal_volume

113

pub_type

杂志文章

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Multiple forms of glucagon and somatostatin isolated from the intestine of the southern-hemisphere lamprey Geotria australis.