Translation

CGRP mRNA

CALCITONIN PRECURSOR (17,500 MW protein |

CGRP PRECURSOR (16.000 MW protein)

CGRP PRECURSOR (16.000 MW protein)

amide

FIGURE 9-4 Model for the production of calcitonin (CT) and calcitonin gene-related peptide (CGRP) via the alternative RNA processing pathways utilized in the expression of the calcitonin gene. The calcitonin gene supports the production of CT in the thyroid and of CGRP in the hypothalamus. Mature CT, which has 32 amino acid residues, and mature CGRP, which has 37 amino acid residues, are derived from different precursor proteins. However, these two precursor proteins have an identical "common region" of 76 amino acid residues, which is derived from the Q and C2 exons of the gene. Reproduced by permission of Rosenfeld, M. G. (1983). Nature (London) 304, 129-135. Copyright © 1983 Macmillan Journals Limited.

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FIGURE 9-4 Model for the production of calcitonin (CT) and calcitonin gene-related peptide (CGRP) via the alternative RNA processing pathways utilized in the expression of the calcitonin gene. The calcitonin gene supports the production of CT in the thyroid and of CGRP in the hypothalamus. Mature CT, which has 32 amino acid residues, and mature CGRP, which has 37 amino acid residues, are derived from different precursor proteins. However, these two precursor proteins have an identical "common region" of 76 amino acid residues, which is derived from the Q and C2 exons of the gene. Reproduced by permission of Rosenfeld, M. G. (1983). Nature (London) 304, 129-135. Copyright © 1983 Macmillan Journals Limited.

are those in which one of the rings of the cyclopenta-noperhydrophenanthrene ring structure of the classic steroids (see Figure 2-2) has undergone fission by breakage of a carbon-carbon bond; in the instance of vitamin D this is the 9, 10-carbon bond of ring B.

There is a family of vitamin D-related steroids depending upon the precise structure of the side chain attached to carbon-17. The vitamin D2 family is derived from ergosterol, while the vitamin D3 family is derived from 7-dehydrocholesterol. The naturally occurring form of vitamin D is that which has the side chain structure identical to that of cholesterol; this is known as vitamin D3 or cholecalciferol. Vitamin D2 or ergocal-ciferol is not a naturally occurring form of the vitamin.

Collectively, vitamin D3 and vitamin D2 can be termed the calciferols or simply vitamin D.

Vitamin D3 is normally produced by exposure to sunlight of the precursor, 7-dehydrocholesterol, present in the skin. Vitamin D2 is produced synthetically via ultraviolet irradiation of the sterol ergosterol. One International Unit (IU) of vitamin D3 is equivalent to 25 ng or 65 pmol. In the United States, the principal form of vitamin D supplementation for food was vitamin D2 in the interval 1930-1965; since 1965 the predominant form of vitamin D supplementation has been vitamin D3. The Recommended Dietary Allowance (RDA) of vitamin D (either D2 or D3) for an adult (ages 25-50) is 200 IU (10 mg), and that for pregnant or

7-dehydrocholesterol (Pro-Vitamin D3 !

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Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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