**7. Concluding remarks**

Autophagy receptor proteins have two main functions: recognizing autophagic cargoes, and interacting with Atg8 homologs. Because of these functions, autophagy receptor proteins can tether autophagic cargoes to the isolation membrane (e.g., Atg19; Figure 2) so that the cargoes are selectively and efficiently engulfed by an autophagosome and transported into the vacuole/lysosome. Although the mechanism of direct interaction with Atg8 homologs

Fig. 2. Atg19 tethers autophagic cargoes to the isolation membrane. Atg19 interacts with prApe1 and Ams1 via the coiled coil domain and ABD, respectively. Atg19 also interacts with Atg8, which is conjugated to phosphatidylethanolamine (PE) and associates with the isolation membrane, via the AIM. Therefore, autophagic cargoes are tethered to the isolation membrane.

via the AIM is common among most autophagy receptor proteins, the recognition mechanisms of autophagic cargoes by autophagy receptor proteins are too divergent to be elucidated. We reported that Atg19 and Atg34 ABDs, similarly to the camelid antibody and monobody, recognize Ams1, an autophagic cargo, using the loops clustered at one side of their immunoglobulin fold. Recent proteomics analysis has identified proteins that are selectively degraded by autophagy (Onodera and Ohsumi, 2004). Although the recognition mechanism of these target proteins by autophagy has not been established, autophagyspecific receptor proteins possessing an ABD-like fold might be responsible. Identification and structural analysis of other autophagy receptor proteins are required for further clarification of the molecular mechanism of specific cargo recognition during autophagy.

#### **8. Acknowledgment**

This work was supported by Grants-in-Aids for Young Scientists (A) from the Ministry of Education, Culture, Sports, Science and Technology of Japan and for JSPS Fellows from Japan Society for the Promotion of Science.

#### **9. References**

390 Biochemistry

Autophagy receptor proteins have two main functions: recognizing autophagic cargoes, and interacting with Atg8 homologs. Because of these functions, autophagy receptor proteins can tether autophagic cargoes to the isolation membrane (e.g., Atg19; Figure 2) so that the cargoes are selectively and efficiently engulfed by an autophagosome and transported into the vacuole/lysosome. Although the mechanism of direct interaction with Atg8 homologs

Fig. 2. Atg19 tethers autophagic cargoes to the isolation membrane. Atg19 interacts with prApe1 and Ams1 via the coiled coil domain and ABD, respectively. Atg19 also interacts with Atg8, which is conjugated to phosphatidylethanolamine (PE) and associates with the isolation membrane, via the AIM. Therefore, autophagic cargoes are tethered to the

via the AIM is common among most autophagy receptor proteins, the recognition mechanisms of autophagic cargoes by autophagy receptor proteins are too divergent to be elucidated. We reported that Atg19 and Atg34 ABDs, similarly to the camelid antibody and monobody, recognize Ams1, an autophagic cargo, using the loops clustered at one side of

**7. Concluding remarks** 

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