Ift56, also known as TTC26, is an IFTB protein essential for cilia formation and function, which are key regulators of animal development. It is involved in the intraflagellar transport (IFT) process, which is crucial for ciliogenesis, ciliary motility, and signaling [1,2,3,4].

In Ift56hop mouse mutants, which are a kind of KO mouse model, cilia have normal distribution but defective structure, with abnormal positioning and number of ciliary microtubule doublets. These cilia cannot efficiently accumulate Gli proteins, leading to developmental patterning defects in Shh signaling-dependent tissues. Core IFTB proteins like IFT88, IFT81, and IFT27 fail to accumulate normally in Ift56hop cilia, while IFTA components remain unaffected, highlighting Ift56's specific role in maintaining IFTB complex integrity [1]. Additionally, in mammalian cells, KIF17, a homodimeric kinesin-2 protein, binds to the IFT46-IFT56 dimer in the IFT-B complex through its C-terminal sequence for its ciliary entry, suggesting Ift56's role in ciliary protein trafficking [2].

In conclusion, Ift56 plays a distinct and crucial role in maintaining IFTB complex integrity, which is essential for cilia structure and function, and ultimately, animal development. The Ift56hop mouse model has provided valuable insights into the role of Ift56 in developmental patterning defects related to abnormal cilia function, potentially contributing to our understanding of diseases associated with ciliary dysfunction [1].