Somatomedin-C (SM-C)

Radioimmunoassay (RIA) for the determination of human Somatomedin-C (SM-C) in serum and plasma. For research use only, not for use in diagnostic procedures.<br><br>

Somatomedin-C (SM-C) or Insulin-like growth factor I (IGF-I) is a basic 70 amino acid single chain polypeptide (MW : 7649 Da) similar to proinsulin (50% sequence homology), and to the other well-characterized member of the somatomedin family : IGF II (67AA, 70 % sequence homology with IGF-I). SM-C is the most important factor, which mediates the growth promoting actions of growth hormone, a pituitary hormone with highly fluctuating blood levels due to pulsatile release. The blood concentration of SM-C is more stable due to the binding to carrier proteins. The concentration of the predominant binding protein (MW 53000) as well as the production of SM-C, are regulated by growth hormone. SM-C is produced by the liver, and other tissues, and it has endocrine, paracrine and autocrine activities. It stimulates growth and regulates differentiation of various tissues, displays insulin-like activities and promotes cartilage growth. Although GH is the most important factor controlling SM-C secretion and concentration, other factors are also determinant: the age (with a peak at adolescence), the sex, the nutritional status, and other hormones (estrogen, thyroxin, prolactin, ...). Specific trophic stimuli mainly control SM-C secretion in the local microenvironment of a particular organ (paracrine activities), while blood SM-C concentration is the most important variable for balanced systemic growth (endocrine activities)