Archive for the 'Inhibin' Category

19 May

Identification of a Nuclear Localization Signal in Activin: DISCUSSION(4)

Since expression of pA mRNA has been detected solely in Sertoli cells, it may be assumed that the protein is taken up by the germ cells after translation in Sertoli cell cytoplasm. Another possibility is that germ cells have their own pA production in an amount not detectable by in situ hybridization. In this case, […]

18 May

Identification of a Nuclear Localization Signal in Activin: DISCUSSION(3)

In its ability for nuclear localization, activin pA appears unique among the activin/inhibin-related proteins. Whereas nuclear pA has been described in addition to testicular tissue also in the central nervous system, nuclear staining of a and pB subunits has not been reported, and in their amino acid sequence they lack any recognizable NLS. The same […]

17 May

Identification of a Nuclear Localization Signal in Activin: DISCUSSION(2)

Mapping of the (3A amino acid sequence upstream of the active NLS revealed a putative endoproteolytic cleavage site 185-RK representing a classical dibasic site requisite for posttranslational processing of many prohormones to biologically active peptides by endoproteolytic enzymes. Cleavage of the (3A precursor at this site would produce a polypeptide sequence having its deduced molecular […]

16 May

Identification of a Nuclear Localization Signal in Activin: DISCUSSION(1)

Activin pA subunit precursor bears within its primary structure two stretches of amino acids that have resemblance to previously described functional NLSs (Fig. 1). In the present study we have shown that the potential for effective nuclear import resides within the bipartite lysine-rich sequence 230-KKKKKEEEGEGKKK. The other possible NLS motif, 276-HRRRRRGLECDGK, proved ineffective on its […]

15 May

Identification of a Nuclear Localization Signal in Activin: RESULTS

NLS The efficiency of nuclear translocation by the two putative NLSs (Fig. 1) of the activin pA subunit precursor is shown in Figure 2. The staining patterns for p-gal activity were classified into four categories as outlined by Ylikomi et al.. Preferential nuclear localization by the lysine-rich sequence 231-244 was detected, with more than 80% […]

14 May

Identification of a Nuclear Localization Signal in Activin: MATERIALS AND METHODS(3)

After thorough washing in TBS, labeled proteins were detected by enhanced chemiluminescence as recommended by the manufacturer. The specificity of the anti-pA antibody had been previously assessed by immunoblotting of recombinant human activin A. The antibody reacted with nonreduced ac-tivin A (apparent Mr 25 000) and the 14 000 Mr pA monomer in reducing conditions. […]

13 May

Identification of a Nuclear Localization Signal in Activin: MATERIALS AND METHODS(2)

Isolation of Cell Nuclei and Preparation of a Nuclear Protein Extract Decapsulated testes from an adult Sprague-Dawley rat were homogenized in 8% sucrose, 25 mM KCl, 5 mM MgCl2, 20 mM tricine/NaOH, pH 7.8, using a glass-poly-tetrafluoroethylene homogenizer. The homogenate was filtered twice through two layers of fine nylon mesh and pelleted at 1000 X […]

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