RBM14-RBM4 protein SIP transcriptional coactivator CoAZ Synaptotagmin-interacting protein COAZ Paraspeckle protein 2 RNA-binding protein 14 PSP2 RBM14 RNA-binding motif protein 14 RRM-containing coactivator activator/modulator RBM14/RBM4 fusion SYT-interacting protein