X0206 3 2016-02-10 0 0001445283 PROTEOSTASIS THERAPEUTICS, INC. PTI 0001661483 Smart Janet L 200 TECHNOLOGY SQUARE, 4TH FLOOR CAMBRIDGE 02139 0 1 0 0 See Remarks Employee Stock Option (Right to Buy) 2.49 2021-12-06 Common Stock 5550 D Employee Stock Option (Right to Buy) 2.49 2022-01-20 Common Stock 273 D Employee Stock Option (Right to Buy) 2.38 2023-03-27 Common Stock 639 D Employee Stock Option (Right to Buy) 3.36 2024-06-06 Common Stock 3006 D Employee Stock Option (Right to Buy) 3.36 2024-06-06 Common Stock 3386 D Employee Stock Option (Right to Buy) 14.71 2025-10-09 Common Stock 9345 D These securities shall vest over a four-year period as follows: 25% on September 26, 2012 and 6.25% each quarter thereafter. These securities shall vest over a four-year period as follows: 25% on January 20, 2013 and 6.25% each quarter thereafter. These securities shall vest over a four-year period as follows: 25% on March 27, 2014 and 6.25% each quarter thereafter. These securities shall vest over a four-year period as follows: 25% on January 30, 2015 and 6.25% each quarter thereafter. These securities shall vest over a four-year period as follows: 25% on January 30, 2015 and 6.25% each quarter thereafter. These securities shall vest over a four-year period as follows: 25% on February 11, 2016 and 6.25% each quarter thereafter. Vice President, Intellectual Property and Legal Affairs Exhibit List - Exhibit 24.1 - Power of Attorney /s/ Janet L. Smart 2016-02-10