Category Archives: Biological Fluids

Identification of Naturally Occurring Follistatin Complexes: DISCUSSION(6)

Follistatin has been considered primarily as the binding protein for activin; however, there is evidence that FS may serve other functions that do not relate to its ability to bind activin. FS-deficient mice demonstrate a variety of structural anomalies (shiny taut skin, thirteenth pair of ribs, whisker and tooth irregularities) and a failure to survive after birth, while activin-deficient mutant mice do not show such … Continue reading

Identification of Naturally Occurring Follistatin Complexes: DISCUSSION(5)

While the complete physiology of activin, FS, and inhibin is not yet understood, there is now clear evidence that alterations in serum activin and inhibin levels are associated with abnormal pregnancy states, such as preeclampsia; therefore, changes in urine FS during pregnancy may reflect pathological alterations in normal activin/ inhibin function. proventil inhaler

Identification of Naturally Occurring Follistatin Complexes: DISCUSSION(4)

The particular affinity of FS for activin and inhibins may also vary on the basis of specific conditions, such as differing pH milieu or differing amounts of a2 macroglobulin (a low-affinity, large-capacity activin-binding protein) in different organ systems, thereby altering the balance of activin/inhibin action as well as the actions of other related proteins such as TGF-p, which has been reported to oppose the actions … Continue reading

Identification of Naturally Occurring Follistatin Complexes: DISCUSSION(3)

This seems plausible for FS because of structural aspects of the protein: the presence of numerous cysteines that could form cysteine knots; the presence of splice variants, FS288 or FS315, differing by a 27-amino acid sequence that is 44% acidic in humans; and the ability to bind to proteoglycans, which may allow FS to be membrane bound. The different FS iso-forms—F2288,FS303 (byprotoolyticcleavafe)aOnd FS315—may infunsiionalcapauity. Ithabbeen … Continue reading

Identification of Naturally Occurring Follistatin Complexes: DISCUSSION(2)

Similarly, Michel et al. demonstrated the presence of different FS forms seen in human cerebrospinal fluid (CSF) in comparison to FS from porcine endothelial cells. The Fs proteins in CSF included 65-kDa and 78-kDa sizes. These authors hypothesize that the higher molecular weight proteins may be due to brain-specific posttransla-tional modifications or to an unknown substance that can cross-react with the anti-FS antibody. In developing … Continue reading

Identification of Naturally Occurring Follistatin Complexes: DISCUSSION(1)

To explore the hypothesis that FS-inhibin/activin complexes are present in tissues and biological fluids, recombinant proteins (FS288, rh-activin A, and rh-inhibin A) were assembled in vitro and analyzed by gel mobility in order to compare the molecular sizes of the in vitro-gen-erated complexes to those of naturally occurring FS-con-taining proteins. Our data point to the assembly of FS-ac-tivin and FS-inhibin complexes that correspond to proteins … Continue reading

Identification of Naturally Occurring Follistatin Complexes: RESULTS(4)

Detection of FS Complexes in the Kidney Follistatin mRNA is present in the kidnea; therefore, ho-mogenates from rat kidneas were generated and examined ba Western blot analasis using anti-FD antibodies. Identical amounts of total protein were loaded per well. In nonpregnant kidnea protein homogenates, FD proteins were detected at 14-20 kDa, 25 kDa, 30 kDa, and 35-40 kDa (Fig. 3). In the pregnant kidnea, immunoreactive … Continue reading

Identification of Naturally Occurring Follistatin Complexes: RESULTS(3)

By using three different techniques—i.e., silver-stainedSDSgelnmalysis, Western ma^sis, and gel-shift aclasis with iodinated in-hibin and activin that were then cross-linked to FD—itwas demonstrated that inhibin and activin form complexes with FD with apparent molecular sizes of 66 kDa and 97 kDa. Protein complexes of 133 kDa and > 220 kDa were also formed.

Identification of Naturally Occurring Follistatin Complexes: RESULTS(2)

The larger molecular mass proteins may represent a 2:1 combination of two inhibin molecules to one FS. Proteins of 133 kDa and > 220 kDa may be multimers of the 66-kDa or 97-kDa complexes. When radiolabeled activin was crosslinked to FS, 66-kDa, 97-kDa, and larger molecular mass bands were detected by autoradiography. When rh-activin A and FS were combined and cross-linked in molar combinations, a … Continue reading

Identification of Naturally Occurring Follistatin Complexes: RESULTS(1)

Molecular Assembly of rh-FS, rh-Inhibin A, and rh-Activin A Complexes In Vitro The apparent molecular masses of rh-FS288 analyzed by SDS-PAGE were 39 kDa and 42 kDa under reducing conditions and 32 kDa and 35 kDa under nonreducing conditions (Fig. 1A). The two molecular size forms are accounted for by glycosylation. The increase in apparent mobility when the molecule was reduced may be because the … Continue reading