SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* PERRIGO Co plc (Last) (First) (Middle) TREASURY BUILDING LOWER GRAND CANAL STREET (Street) DUBLIN L2 2 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol PROTEOSTASIS THERAPEUTICS, INC. [ PTI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 02/10/2016
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	02/17/2016		C		2,416,612(1)	A	(1)	2,416,612	I	See footnote(3)
Common Stock	02/17/2016		C		366,455(2)	A	(2)	2,783,067	I	See footnote(3)
Common Strock	02/17/2016		P		125,000(4)	A	$8	2,908,067	I	See footnote(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Convertible Redeemable Preferred Stock	(1)	02/17/2016		C			20,000,000	(1)	(1)	Common Stock	2,416,612	$0	0	I	See footnote(3)
Series B Convertible Redeemable Preferred Stock	(2)	02/17/2016		C			3,961,459	(2)	(2)	Common Stock	366,455	$0	0	I	See footnote(3)
Stock Option (Right to Buy)	$8	02/10/2016		A		45,760		(5)	02/10/2016	Common Stock	45,760	$0	45,760	I	See footnote(6)

1. Name and Address of Reporting Person* PERRIGO Co plc (Last) (First) (Middle) TREASURY BUILDING LOWER GRAND CANAL STREET (Street) DUBLIN L2 2 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* PERRIGO HOLDINGS LTD. (Last) (First) (Middle) TREASURY BUILDING, LOWER GRAND CANAL STREET (Street) DUBLIN L2 2 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* ELAN PHARMA INTERNATIONAL LTD. (Last) (First) (Middle) TREASURY BUILDING, LOWER GRAND CANAL STREET (Street) DUBLIN L2 2 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* PERRIGO CORP LTD. (Last) (First) (Middle) TREASURY BUILDING, LOWER GRAND CANAL ST (Street) DUBLIN 2 L2 2 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* PERRIGO SCIENCE ONE LTD. (Last) (First) (Middle) TREASURY BUILDING, LOWER GRAND CANAL STREET (Street) DUBLIN L2 2 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. The Series A Convertible Redeemable Preferred Stock (the "Series A Shares") automatically converted on a 10.8102-to-1 basis into the Issuer's Common Stock, together with the accrued but unpaid dividends, upon closing of the Issuer's initial public offering into 2,416,612 shares of the Issuer's Common Stock. The Series A Shares did not have an expiration date.

2. The Series B Convertible Redeemable Preferred Stock (the "Series B Shares") automatically converted on a 10.8102-to-1 basis into the Issuer's Common Stock upon closing of the Issuer's initial public offering into 366,455 shares of the Issuer's Common Stock. The Series B Shares did not have an expiration date.

3. Perrigo Science One Ltd. ("Science") (formerly Elan Science One Ltd.) is the direct owner of these securities. Science is a direct or indirect, wholly-owned subsidiary of each of the other reporting persons.

4. These securities were purchased in connection with the initial public offering of the Issuer.

5. These securities shall vest and become exercisable in equal quarterly installments starting on February 10, 2016 until the option is fully vested and exercisable on February 10, 2019, subject to continued service.

6. Perrigo Company plc ("Perrigo") and the other reporting persons named herein may be deemed to beneficially own the 45,760 options granted to Mr. Walshe in his capacity as a director of Proteostasis Therapeutics, Inc. (the "Company"). Mr. Walshe has an understanding with Perrigo pursuant to which he holds such securities for the benefit of Perrigo.

Remarks:

	/s/Todd Kingma, Secretary of Perrigo Company plc	02/18/2016
	/s/Todd Kingma, Secretary of Perrigo Holdings Ltd.	02/18/2016
	/s/Todd Kingma, Director of Elan Pharma International Limited	02/18/2016
	/s/Todd Kingma, Secretary of Perrigo Corporation Limited	02/18/2016
	/s/Todd Kingma, Secretary of Perrigo Science One Ltd.	02/18/2016
	** Signature of Reporting Person	Date
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