The following text describes a protein:
Function:
Stable structural component of the perinuclear meiotic nuage, a germline-specific subcellular membraneless ribonucleoprotein compartment involved in production of transposable element-repressing Piwi-interacting RNA (piRNA)-induced silencing complexes (piRISCs), which are essential for maintaining germline integrity during oogenesis. Scaffold component of the ping-pong piRNA processing (4P) complex that recruits the Piwi proteins aub and AGO3 to specific subregions of the nuage where it coordinates their activity in the ping-pong amplification step of secondary piRNA biogenesis. Binds methylated aub, which is associated with piRNA, and unmethylated AGO3, which is not associated with piRNA, bringing the Piwi proteins into close proximity and facilitating the loading of freshly cut piRNAs generated by aub onto AGO3. Promotes asymmetric ping-pong amplification by aub and AGO3 to bias production towards antisense piRNAs capable of silencing transposable elements. Required for symmetrical dimethylation of AGO3, probably by recruitment to the nuage where methylosome components are located; dimethylation promotes AGO3 dissociation and interaction with other tudor-domain containing proteins such as tud. Required for the recruitment of mael to the perinuclear meiotic nuage. Required for the recruitment of aub to the nuage in testes but not in ovaries. Involved in repression of long interspersed nuclear elements (LINEs) including HeT-A, I-element LINEs and possibly mst40, but not TART LINEs.
Subcellular Localization:
Cytoplasm. Cytoplasm, perinuclear region. Cytoplasm, Cytoplasmic ribonucleoprotein granule. Note=Component of the perinuclear meiotic nuage (also known as germline granule or P granule), a germline-specific membraneless ribonucleoprotein biocondensate involved in post-transcriptional regulation of transposons and mRNAs. Colocalizes with vas/vasa in the perinuclear nuage but not the pole plasm. Localization to the nuage is dependent on spn-E, vas and aub but not mael or AGO3. Localization to the nuage does not require tub in ovaries but does in testes; tub and aub are required for krimp protein stability in testes.
Domain:
Possesses two tudor domains, a C-terminal canonical tudor domain and a central non-canonical tudor domain (Probable). Both tudor domains can interact with Piwi proteins allowing the simultaneous binding of aub and AGO3; this brings them in close proximity to facilitate their role in ping-pong ampification of piRNAs. The canonical tudor domain possesses a hydrophobic pocket that preferentially binds methylated aub; the interaction requires symmetrical methylation on at least one aub N-terminal arginine. The non-canonical tudor domain possesses a hydrophilic binding pocket that preferentially binds unmethylated AGO3; methylation on any of the AGO3 N-terminal arginines disrupts this interaction. The differential binding preference ensures recruitment of one piRNA loaded (aub) and one unloaded (AGO3) Piwi-protein; the methylation state of the Piwi proteins acts as an indicator of their piRNA binding state.
Sequence:
MNLEDISMIMKLFDSNMHKLQGNLRSYQTEMHQIHKELTEKLSHADLLYRSLIPLHDHLVASLSEVNAHVMKLNVQLHINRQSVRLGDYEYYEKSIDNPYSSIRSGLQAIEKPGCAEAICQSSKPAFVECLPSSTSEEVPVVAVQEASSTNQLDAISVVNENLSEERDATPQPLAVSKNMEETMPSNPFHEQLEGSLEEIPVGSKIVVETEKANNPVRSEASAPATSDNQSLLAAKQGTQTIGTGICNKISKSTINMPNNWQLENPTEVTAASIEKVNKLPKSPRNRFLLPPKGGTETTRRDIYNQILKDMAAFPENTIVTAVLASVDVTDNCAYVAKWDESSDRIKKVLQRQLPLQELDQLPDYGDIFAVLDSINNIITRITINSSSAGGGYDAYLIDFGEHIHFDGNETIFKLPDDIKRLPAQAIRCDLINCDIANMHCFVNTYIKIRVHENNNSTLVAEPVIDRLSRPTKTNTTKYPAGITEDDMAMLNEIDESTSDPLKAVLGFRPKDEQRICRHYDPKLNGCFKGNNCRFAHEPFAPNGATKDVELARALPETIFDTTVHFEIGSIVGILITFINGPTEVYGQFLDGSPPLVWDKKDVPENKRTFKSKPRLLDIVLALYSDGCFYRAQIIDEFPSEYMIFYVDYGNTEFVPLSCLAPCENVDSFKPHRVFSFHIEGIVRSKNLTHQKTIECIEYLKSKLLNTEMNVHLVQRLPDGFLIRFLDDWKYIPEQLLQRNYAQVSQ